diff --git a/app/controllers/admin/sign_in_token_authentications_controller.rb b/app/controllers/admin/sign_in_token_authentications_controller.rb
deleted file mode 100644
index e620ab2926d..00000000000
--- a/app/controllers/admin/sign_in_token_authentications_controller.rb
+++ /dev/null
@@ -1,27 +0,0 @@
-# frozen_string_literal: true
-
-module Admin
-  class SignInTokenAuthenticationsController < BaseController
-    before_action :set_target_user
-
-    def create
-      authorize @user, :enable_sign_in_token_auth?
-      @user.update(skip_sign_in_token: false)
-      log_action :enable_sign_in_token_auth, @user
-      redirect_to admin_account_path(@user.account_id)
-    end
-
-    def destroy
-      authorize @user, :disable_sign_in_token_auth?
-      @user.update(skip_sign_in_token: true)
-      log_action :disable_sign_in_token_auth, @user
-      redirect_to admin_account_path(@user.account_id)
-    end
-
-    private
-
-    def set_target_user
-      @user = User.find(params[:user_id])
-    end
-  end
-end
diff --git a/app/controllers/api/v1/admin/account_actions_controller.rb b/app/controllers/api/v1/admin/account_actions_controller.rb
index 15af50822e3..6c9e04402c9 100644
--- a/app/controllers/api/v1/admin/account_actions_controller.rb
+++ b/app/controllers/api/v1/admin/account_actions_controller.rb
@@ -1,8 +1,6 @@
 # frozen_string_literal: true
 
 class Api::V1::Admin::AccountActionsController < Api::BaseController
-  protect_from_forgery with: :exception
-
   before_action -> { authorize_if_got_token! :'admin:write', :'admin:write:accounts' }
   before_action :require_staff!
   before_action :set_account
diff --git a/app/controllers/api/v1/admin/accounts_controller.rb b/app/controllers/api/v1/admin/accounts_controller.rb
index 4b6dab20819..dc9d3402fb4 100644
--- a/app/controllers/api/v1/admin/accounts_controller.rb
+++ b/app/controllers/api/v1/admin/accounts_controller.rb
@@ -1,8 +1,6 @@
 # frozen_string_literal: true
 
 class Api::V1::Admin::AccountsController < Api::BaseController
-  protect_from_forgery with: :exception
-
   include Authorization
   include AccountableConcern
 
diff --git a/app/controllers/api/v1/admin/dimensions_controller.rb b/app/controllers/api/v1/admin/dimensions_controller.rb
index b1f73899019..49a5be1c365 100644
--- a/app/controllers/api/v1/admin/dimensions_controller.rb
+++ b/app/controllers/api/v1/admin/dimensions_controller.rb
@@ -1,8 +1,6 @@
 # frozen_string_literal: true
 
 class Api::V1::Admin::DimensionsController < Api::BaseController
-  protect_from_forgery with: :exception
-
   before_action -> { authorize_if_got_token! :'admin:read' }
   before_action :require_staff!
   before_action :set_dimensions
diff --git a/app/controllers/api/v1/admin/measures_controller.rb b/app/controllers/api/v1/admin/measures_controller.rb
index d64c3cdf704..da95d34220d 100644
--- a/app/controllers/api/v1/admin/measures_controller.rb
+++ b/app/controllers/api/v1/admin/measures_controller.rb
@@ -1,8 +1,6 @@
 # frozen_string_literal: true
 
 class Api::V1::Admin::MeasuresController < Api::BaseController
-  protect_from_forgery with: :exception
-
   before_action -> { authorize_if_got_token! :'admin:read' }
   before_action :require_staff!
   before_action :set_measures
diff --git a/app/controllers/api/v1/admin/reports_controller.rb b/app/controllers/api/v1/admin/reports_controller.rb
index fbfd0ee128c..865ba3d23c8 100644
--- a/app/controllers/api/v1/admin/reports_controller.rb
+++ b/app/controllers/api/v1/admin/reports_controller.rb
@@ -1,8 +1,6 @@
 # frozen_string_literal: true
 
 class Api::V1::Admin::ReportsController < Api::BaseController
-  protect_from_forgery with: :exception
-
   include Authorization
   include AccountableConcern
 
diff --git a/app/controllers/api/v1/admin/retention_controller.rb b/app/controllers/api/v1/admin/retention_controller.rb
index 4af5a5c4dcc..98d1a3d813f 100644
--- a/app/controllers/api/v1/admin/retention_controller.rb
+++ b/app/controllers/api/v1/admin/retention_controller.rb
@@ -1,8 +1,6 @@
 # frozen_string_literal: true
 
 class Api::V1::Admin::RetentionController < Api::BaseController
-  protect_from_forgery with: :exception
-
   before_action -> { authorize_if_got_token! :'admin:read' }
   before_action :require_staff!
   before_action :set_cohorts
diff --git a/app/controllers/api/v1/admin/trends/links_controller.rb b/app/controllers/api/v1/admin/trends/links_controller.rb
index 63b3d9358e0..0a191fe4b26 100644
--- a/app/controllers/api/v1/admin/trends/links_controller.rb
+++ b/app/controllers/api/v1/admin/trends/links_controller.rb
@@ -1,8 +1,6 @@
 # frozen_string_literal: true
 
 class Api::V1::Admin::Trends::LinksController < Api::BaseController
-  protect_from_forgery with: :exception
-
   before_action -> { authorize_if_got_token! :'admin:read' }
   before_action :require_staff!
   before_action :set_links
diff --git a/app/controllers/api/v1/admin/trends/statuses_controller.rb b/app/controllers/api/v1/admin/trends/statuses_controller.rb
index 86633cc7430..cb145f165c3 100644
--- a/app/controllers/api/v1/admin/trends/statuses_controller.rb
+++ b/app/controllers/api/v1/admin/trends/statuses_controller.rb
@@ -1,8 +1,6 @@
 # frozen_string_literal: true
 
 class Api::V1::Admin::Trends::StatusesController < Api::BaseController
-  protect_from_forgery with: :exception
-
   before_action -> { authorize_if_got_token! :'admin:read' }
   before_action :require_staff!
   before_action :set_statuses
diff --git a/app/controllers/api/v1/admin/trends/tags_controller.rb b/app/controllers/api/v1/admin/trends/tags_controller.rb
index 5cc4c269d71..9c28b0412b4 100644
--- a/app/controllers/api/v1/admin/trends/tags_controller.rb
+++ b/app/controllers/api/v1/admin/trends/tags_controller.rb
@@ -1,8 +1,6 @@
 # frozen_string_literal: true
 
 class Api::V1::Admin::Trends::TagsController < Api::BaseController
-  protect_from_forgery with: :exception
-
   before_action -> { authorize_if_got_token! :'admin:read' }
   before_action :require_staff!
   before_action :set_tags
diff --git a/app/controllers/api/v1/trends/tags_controller.rb b/app/controllers/api/v1/trends/tags_controller.rb
index d77857871ac..329ef5ae73c 100644
--- a/app/controllers/api/v1/trends/tags_controller.rb
+++ b/app/controllers/api/v1/trends/tags_controller.rb
@@ -16,7 +16,7 @@ class Api::V1::Trends::TagsController < Api::BaseController
   def set_tags
     @tags = begin
       if Setting.trends
-        Trends.tags.query.allowed.limit(limit_param(DEFAULT_TAGS_LIMIT))
+        Trends.tags.query.allowed.offset(offset_param).limit(limit_param(DEFAULT_TAGS_LIMIT))
       else
         []
       end
diff --git a/app/controllers/auth/sessions_controller.rb b/app/controllers/auth/sessions_controller.rb
index 8607077f71e..056f8a9f101 100644
--- a/app/controllers/auth/sessions_controller.rb
+++ b/app/controllers/auth/sessions_controller.rb
@@ -10,7 +10,6 @@ class Auth::SessionsController < Devise::SessionsController
   prepend_before_action :set_pack
 
   include TwoFactorAuthenticationConcern
-  include SignInTokenAuthenticationConcern
 
   before_action :set_instance_presenter, only: [:new]
   before_action :set_body_classes
@@ -68,7 +67,7 @@ class Auth::SessionsController < Devise::SessionsController
   end
 
   def user_params
-    params.require(:user).permit(:email, :password, :otp_attempt, :sign_in_token_attempt, credential: {})
+    params.require(:user).permit(:email, :password, :otp_attempt, credential: {})
   end
 
   def after_sign_in_path_for(resource)
@@ -148,6 +147,12 @@ class Auth::SessionsController < Devise::SessionsController
       ip: request.remote_ip,
       user_agent: request.user_agent
     )
+
+    UserMailer.suspicious_sign_in(user, request.remote_ip, request.user_agent, Time.now.utc).deliver_later! if suspicious_sign_in?(user)
+  end
+
+  def suspicious_sign_in?(user)
+    SuspiciousSignInDetector.new(user).suspicious?(request)
   end
 
   def on_authentication_failure(user, security_measure, failure_reason)
diff --git a/app/controllers/concerns/sign_in_token_authentication_concern.rb b/app/controllers/concerns/sign_in_token_authentication_concern.rb
deleted file mode 100644
index 4eb3d7181cb..00000000000
--- a/app/controllers/concerns/sign_in_token_authentication_concern.rb
+++ /dev/null
@@ -1,57 +0,0 @@
-# frozen_string_literal: true
-
-module SignInTokenAuthenticationConcern
-  extend ActiveSupport::Concern
-
-  included do
-    prepend_before_action :authenticate_with_sign_in_token, if: :sign_in_token_required?, only: [:create]
-  end
-
-  def sign_in_token_required?
-    find_user&.suspicious_sign_in?(request.remote_ip)
-  end
-
-  def valid_sign_in_token_attempt?(user)
-    Devise.secure_compare(user.sign_in_token, user_params[:sign_in_token_attempt])
-  end
-
-  def authenticate_with_sign_in_token
-    if user_params[:email].present?
-      user = self.resource = find_user_from_params
-      prompt_for_sign_in_token(user) if user&.external_or_valid_password?(user_params[:password])
-    elsif session[:attempt_user_id]
-      user = self.resource = User.find_by(id: session[:attempt_user_id])
-      return if user.nil?
-
-      if session[:attempt_user_updated_at] != user.updated_at.to_s
-        restart_session
-      elsif user_params.key?(:sign_in_token_attempt)
-        authenticate_with_sign_in_token_attempt(user)
-      end
-    end
-  end
-
-  def authenticate_with_sign_in_token_attempt(user)
-    if valid_sign_in_token_attempt?(user)
-      on_authentication_success(user, :sign_in_token)
-    else
-      on_authentication_failure(user, :sign_in_token, :invalid_sign_in_token)
-      flash.now[:alert] = I18n.t('users.invalid_sign_in_token')
-      prompt_for_sign_in_token(user)
-    end
-  end
-
-  def prompt_for_sign_in_token(user)
-    if user.sign_in_token_expired?
-      user.generate_sign_in_token && user.save
-      UserMailer.sign_in_token(user, request.remote_ip, request.user_agent, Time.now.utc.to_s).deliver_later!
-    end
-
-    set_attempt_session(user)
-    use_pack 'auth'
-
-    @body_classes = 'lighter'
-
-    set_locale { render :sign_in_token }
-  end
-end
diff --git a/app/javascript/flavours/glitch/reducers/timelines.js b/app/javascript/flavours/glitch/reducers/timelines.js
index 7d815d8503a..b40e74c5bc6 100644
--- a/app/javascript/flavours/glitch/reducers/timelines.js
+++ b/app/javascript/flavours/glitch/reducers/timelines.js
@@ -16,7 +16,7 @@ import {
   ACCOUNT_MUTE_SUCCESS,
   ACCOUNT_UNFOLLOW_SUCCESS,
 } from 'flavours/glitch/actions/accounts';
-import { Map as ImmutableMap, List as ImmutableList, fromJS } from 'immutable';
+import { Map as ImmutableMap, List as ImmutableList, OrderedSet as ImmutableOrderedSet, fromJS } from 'immutable';
 import compareId from 'flavours/glitch/util/compare_id';
 
 const initialState = ImmutableMap();
@@ -32,6 +32,13 @@ const initialTimeline = ImmutableMap({
 });
 
 const expandNormalizedTimeline = (state, timeline, statuses, next, isPartial, isLoadingRecent, usePendingItems) => {
+  // This method is pretty tricky because:
+  // - existing items in the timeline might be out of order
+  // - the existing timeline may have gaps, most often explicitly noted with a `null` item
+  // - ideally, we don't want it to reorder existing items of the timeline
+  // - `statuses` may include items that are already included in the timeline
+  // - this function can be called either to fill in a gap, or load newer items
+
   return state.update(timeline, initialTimeline, map => map.withMutations(mMap => {
     mMap.set('isLoading', false);
     mMap.set('isPartial', isPartial);
@@ -45,15 +52,34 @@ const expandNormalizedTimeline = (state, timeline, statuses, next, isPartial, is
 
       mMap.update(usePendingItems ? 'pendingItems' : 'items', ImmutableList(), oldIds => {
         const newIds = statuses.map(status => status.get('id'));
-        const lastIndex = oldIds.findLastIndex(id => id !== null && compareId(id, newIds.last()) >= 0) + 1;
-        const firstIndex = oldIds.take(lastIndex).findLastIndex(id => id !== null && compareId(id, newIds.first()) > 0);
 
-        if (firstIndex < 0) {
-          return (isPartial ? newIds.unshift(null) : newIds).concat(oldIds.skip(lastIndex));
+        // Now this gets tricky, as we don't necessarily know for sure where the gap to fill is
+        // and some items in the timeline may not be properly ordered.
+
+        // However, we know that `newIds.last()` is the oldest item that was requested and that
+        // there is no “hole” between `newIds.last()` and `newIds.first()`.
+
+        // First, find the furthest (if properly sorted, oldest) item in the timeline that is
+        // newer than the oldest fetched one, as it's most likely that it delimits the gap.
+        // Start the gap *after* that item.
+        const lastIndex = oldIds.findLastIndex(id => id !== null && compareId(id, newIds.last()) >= 0) + 1;
+
+        // Then, try to find the furthest (if properly sorted, oldest) item in the timeline that
+        // is newer than the most recent fetched one, as it delimits a section comprised of only
+        // items present in `newIds` (or that were deleted from the server, so should be removed
+        // anyway).
+        // Stop the gap *after* that item.
+        const firstIndex = oldIds.take(lastIndex).findLastIndex(id => id !== null && compareId(id, newIds.first()) > 0) + 1;
+
+        // Make sure we aren't inserting duplicates
+        let insertedIds = ImmutableOrderedSet(newIds).subtract(oldIds.take(firstIndex), oldIds.skip(lastIndex)).toList();
+        // Finally, insert a gap marker if the data is marked as partial by the server
+        if (isPartial && (firstIndex === 0 || oldIds.get(firstIndex - 1) !== null)) {
+          insertedIds = insertedIds.unshift(null);
         }
 
-        return oldIds.take(firstIndex + 1).concat(
-          isPartial && oldIds.get(firstIndex) !== null ? newIds.unshift(null) : newIds,
+        return oldIds.take(firstIndex).concat(
+          insertedIds,
           oldIds.skip(lastIndex),
         );
       });
diff --git a/app/javascript/mastodon/reducers/timelines.js b/app/javascript/mastodon/reducers/timelines.js
index b66c19fd5e8..301997567f7 100644
--- a/app/javascript/mastodon/reducers/timelines.js
+++ b/app/javascript/mastodon/reducers/timelines.js
@@ -16,7 +16,7 @@ import {
   ACCOUNT_MUTE_SUCCESS,
   ACCOUNT_UNFOLLOW_SUCCESS,
 } from '../actions/accounts';
-import { Map as ImmutableMap, List as ImmutableList, fromJS } from 'immutable';
+import { Map as ImmutableMap, List as ImmutableList, OrderedSet as ImmutableOrderedSet, fromJS } from 'immutable';
 import compareId from '../compare_id';
 
 const initialState = ImmutableMap();
@@ -32,6 +32,13 @@ const initialTimeline = ImmutableMap({
 });
 
 const expandNormalizedTimeline = (state, timeline, statuses, next, isPartial, isLoadingRecent, usePendingItems) => {
+  // This method is pretty tricky because:
+  // - existing items in the timeline might be out of order
+  // - the existing timeline may have gaps, most often explicitly noted with a `null` item
+  // - ideally, we don't want it to reorder existing items of the timeline
+  // - `statuses` may include items that are already included in the timeline
+  // - this function can be called either to fill in a gap, or load newer items
+
   return state.update(timeline, initialTimeline, map => map.withMutations(mMap => {
     mMap.set('isLoading', false);
     mMap.set('isPartial', isPartial);
@@ -46,15 +53,33 @@ const expandNormalizedTimeline = (state, timeline, statuses, next, isPartial, is
       mMap.update(usePendingItems ? 'pendingItems' : 'items', ImmutableList(), oldIds => {
         const newIds = statuses.map(status => status.get('id'));
 
-        const lastIndex = oldIds.findLastIndex(id => id !== null && compareId(id, newIds.last()) >= 0) + 1;
-        const firstIndex = oldIds.take(lastIndex).findLastIndex(id => id !== null && compareId(id, newIds.first()) > 0);
+        // Now this gets tricky, as we don't necessarily know for sure where the gap to fill is
+        // and some items in the timeline may not be properly ordered.
 
-        if (firstIndex < 0) {
-          return (isPartial ? newIds.unshift(null) : newIds).concat(oldIds.skip(lastIndex));
+        // However, we know that `newIds.last()` is the oldest item that was requested and that
+        // there is no “hole” between `newIds.last()` and `newIds.first()`.
+
+        // First, find the furthest (if properly sorted, oldest) item in the timeline that is
+        // newer than the oldest fetched one, as it's most likely that it delimits the gap.
+        // Start the gap *after* that item.
+        const lastIndex = oldIds.findLastIndex(id => id !== null && compareId(id, newIds.last()) >= 0) + 1;
+
+        // Then, try to find the furthest (if properly sorted, oldest) item in the timeline that
+        // is newer than the most recent fetched one, as it delimits a section comprised of only
+        // items present in `newIds` (or that were deleted from the server, so should be removed
+        // anyway).
+        // Stop the gap *after* that item.
+        const firstIndex = oldIds.take(lastIndex).findLastIndex(id => id !== null && compareId(id, newIds.first()) > 0) + 1;
+
+        // Make sure we aren't inserting duplicates
+        let insertedIds = ImmutableOrderedSet(newIds).subtract(oldIds.take(firstIndex), oldIds.skip(lastIndex)).toList();
+        // Finally, insert a gap marker if the data is marked as partial by the server
+        if (isPartial && (firstIndex === 0 || oldIds.get(firstIndex - 1) !== null)) {
+          insertedIds = insertedIds.unshift(null);
         }
 
-        return oldIds.take(firstIndex + 1).concat(
-          isPartial && oldIds.get(firstIndex) !== null ? newIds.unshift(null) : newIds,
+        return oldIds.take(firstIndex).concat(
+          insertedIds,
           oldIds.skip(lastIndex),
         );
       });
diff --git a/app/javascript/styles/mailer.scss b/app/javascript/styles/mailer.scss
index 34852178e35..18fe522eb20 100644
--- a/app/javascript/styles/mailer.scss
+++ b/app/javascript/styles/mailer.scss
@@ -435,6 +435,10 @@ h5 {
     background: $success-green;
   }
 
+  &.warning-icon td {
+    background: $gold-star;
+  }
+
   &.alert-icon td {
     background: $error-red;
   }
diff --git a/app/lib/suspicious_sign_in_detector.rb b/app/lib/suspicious_sign_in_detector.rb
new file mode 100644
index 00000000000..1af5188c658
--- /dev/null
+++ b/app/lib/suspicious_sign_in_detector.rb
@@ -0,0 +1,42 @@
+# frozen_string_literal: true
+
+class SuspiciousSignInDetector
+  IPV6_TOLERANCE_MASK = 64
+  IPV4_TOLERANCE_MASK = 16
+
+  def initialize(user)
+    @user = user
+  end
+
+  def suspicious?(request)
+    !sufficient_security_measures? && !freshly_signed_up? && !previously_seen_ip?(request)
+  end
+
+  private
+
+  def sufficient_security_measures?
+    @user.otp_required_for_login?
+  end
+
+  def previously_seen_ip?(request)
+    @user.ips.where('ip <<= ?', masked_ip(request)).exists?
+  end
+
+  def freshly_signed_up?
+    @user.current_sign_in_at.blank?
+  end
+
+  def masked_ip(request)
+    masked_ip_addr = begin
+      ip_addr = IPAddr.new(request.remote_ip)
+
+      if ip_addr.ipv6?
+        ip_addr.mask(IPV6_TOLERANCE_MASK)
+      else
+        ip_addr.mask(IPV4_TOLERANCE_MASK)
+      end
+    end
+
+    "#{masked_ip_addr}/#{masked_ip_addr.prefix}"
+  end
+end
diff --git a/app/mailers/user_mailer.rb b/app/mailers/user_mailer.rb
index 1a823328c4f..ce36dd6f5f7 100644
--- a/app/mailers/user_mailer.rb
+++ b/app/mailers/user_mailer.rb
@@ -167,9 +167,7 @@ class UserMailer < Devise::Mailer
     @statuses = @warning.statuses.includes(:account, :preloadable_poll, :media_attachments, active_mentions: [:account])
 
     I18n.with_locale(@resource.locale || I18n.default_locale) do
-      mail to: @resource.email,
-           subject: I18n.t("user_mailer.warning.subject.#{@warning.action}", acct: "@#{user.account.local_username_and_domain}"),
-           reply_to: ENV['SMTP_REPLY_TO']
+      mail to: @resource.email, subject: I18n.t("user_mailer.warning.subject.#{@warning.action}", acct: "@#{user.account.local_username_and_domain}")
     end
   end
 
@@ -193,7 +191,7 @@ class UserMailer < Devise::Mailer
     end
   end
 
-  def sign_in_token(user, remote_ip, user_agent, timestamp)
+  def suspicious_sign_in(user, remote_ip, user_agent, timestamp)
     @resource   = user
     @instance   = Rails.configuration.x.local_domain
     @remote_ip  = remote_ip
@@ -201,12 +199,8 @@ class UserMailer < Devise::Mailer
     @detection  = Browser.new(user_agent)
     @timestamp  = timestamp.to_time.utc
 
-    return unless @resource.active_for_authentication?
-
     I18n.with_locale(@resource.locale || I18n.default_locale) do
-      mail to: @resource.email,
-           subject: I18n.t('user_mailer.sign_in_token.subject'),
-           reply_to: ENV['SMTP_REPLY_TO']
+      mail to: @resource.email, subject: I18n.t('user_mailer.suspicious_sign_in.subject')
     end
   end
 end
diff --git a/app/models/user.rb b/app/models/user.rb
index 76ad7d1b208..5dd93519c87 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -47,6 +47,7 @@ class User < ApplicationRecord
     remember_token
     current_sign_in_ip
     last_sign_in_ip
+    skip_sign_in_token
   )
 
   include Settings::Extend
@@ -132,7 +133,7 @@ class User < ApplicationRecord
            :disable_swiping, :default_content_type, :system_emoji_font,
            to: :settings, prefix: :setting, allow_nil: false
 
-  attr_reader :invite_code, :sign_in_token_attempt
+  attr_reader :invite_code
   attr_writer :external, :bypass_invite_request_check
 
   def confirmed?
@@ -200,10 +201,6 @@ class User < ApplicationRecord
     !account.memorial?
   end
 
-  def suspicious_sign_in?(ip)
-    !otp_required_for_login? && !skip_sign_in_token? && current_sign_in_at.present? && !ips.where(ip: ip).exists?
-  end
-
   def functional?
     confirmed? && approved? && !disabled? && !account.suspended? && !account.memorial?
   end
@@ -376,15 +373,6 @@ class User < ApplicationRecord
     setting_display_media == 'hide_all'
   end
 
-  def sign_in_token_expired?
-    sign_in_token_sent_at.nil? || sign_in_token_sent_at < 5.minutes.ago
-  end
-
-  def generate_sign_in_token
-    self.sign_in_token         = Devise.friendly_token(6)
-    self.sign_in_token_sent_at = Time.now.utc
-  end
-
   protected
 
   def send_devise_notification(notification, *args, **kwargs)
diff --git a/app/policies/user_policy.rb b/app/policies/user_policy.rb
index 92e2c4f4bba..140905e1f22 100644
--- a/app/policies/user_policy.rb
+++ b/app/policies/user_policy.rb
@@ -13,14 +13,6 @@ class UserPolicy < ApplicationPolicy
     admin? && !record.staff?
   end
 
-  def disable_sign_in_token_auth?
-    staff?
-  end
-
-  def enable_sign_in_token_auth?
-    staff?
-  end
-
   def confirm?
     staff? && !record.confirmed?
   end
diff --git a/app/services/activitypub/fetch_featured_collection_service.rb b/app/services/activitypub/fetch_featured_collection_service.rb
index 780741feb3a..66234b7111a 100644
--- a/app/services/activitypub/fetch_featured_collection_service.rb
+++ b/app/services/activitypub/fetch_featured_collection_service.rb
@@ -22,9 +22,19 @@ class ActivityPub::FetchFeaturedCollectionService < BaseService
   private
 
   def process_items(items)
-    status_ids = items.map { |item| value_or_id(item) }
-                      .filter_map { |uri| ActivityPub::FetchRemoteStatusService.new.call(uri, on_behalf_of: local_follower) unless ActivityPub::TagManager.instance.local_uri?(uri) }
-                      .filter_map { |status| status.id if status.account_id == @account.id }
+    status_ids = items.filter_map do |item|
+      uri = value_or_id(item)
+      next if ActivityPub::TagManager.instance.local_uri?(uri)
+
+      status = ActivityPub::FetchRemoteStatusService.new.call(uri, on_behalf_of: local_follower)
+      next unless status.account_id == @account.id
+
+      status.id
+    rescue ActiveRecord::RecordInvalid => e
+      Rails.logger.debug "Invalid pinned status #{uri}: #{e.message}"
+      nil
+    end
+
     to_remove = []
     to_add    = status_ids
 
diff --git a/app/services/activitypub/process_status_update_service.rb b/app/services/activitypub/process_status_update_service.rb
index 6dc14d8c2a1..3d9d9cb8462 100644
--- a/app/services/activitypub/process_status_update_service.rb
+++ b/app/services/activitypub/process_status_update_service.rb
@@ -17,10 +17,19 @@ class ActivityPub::ProcessStatusUpdateService < BaseService
     # Only native types can be updated at the moment
     return @status if !expected_type? || already_updated_more_recently?
 
-    last_edit_date = status.edited_at.presence || status.created_at
+    if @status_parser.edited_at.present? && (@status.edited_at.nil? || @status_parser.edited_at > @status.edited_at)
+      handle_explicit_update!
+    else
+      handle_implicit_update!
+    end
 
-    # Since we rely on tracking of previous changes, ensure clean slate
-    status.clear_changes_information
+    @status
+  end
+
+  private
+
+  def handle_explicit_update!
+    last_edit_date = @status.edited_at.presence || @status.created_at
 
     # Only allow processing one create/update per status at a time
     RedisLock.acquire(lock_options) do |lock|
@@ -45,12 +54,20 @@ class ActivityPub::ProcessStatusUpdateService < BaseService
       end
     end
 
-    forward_activity! if significant_changes? && @status_parser.edited_at.present? && @status_parser.edited_at > last_edit_date
-
-    @status
+    forward_activity! if significant_changes? && @status_parser.edited_at > last_edit_date
   end
 
-  private
+  def handle_implicit_update!
+    RedisLock.acquire(lock_options) do |lock|
+      if lock.acquired?
+        update_poll!(allow_significant_changes: false)
+      else
+        raise Mastodon::RaceConditionError
+      end
+    end
+
+    queue_poll_notifications!
+  end
 
   def update_media_attachments!
     previous_media_attachments     = @status.media_attachments.to_a
@@ -98,7 +115,7 @@ class ActivityPub::ProcessStatusUpdateService < BaseService
     @media_attachments_changed = true if @status.ordered_media_attachment_ids != previous_media_attachments_ids
   end
 
-  def update_poll!
+  def update_poll!(allow_significant_changes: true)
     previous_poll        = @status.preloadable_poll
     @previous_expires_at = previous_poll&.expires_at
     poll_parser          = ActivityPub::Parser::PollParser.new(@json)
@@ -109,6 +126,7 @@ class ActivityPub::ProcessStatusUpdateService < BaseService
       # If for some reasons the options were changed, it invalidates all previous
       # votes, so we need to remove them
       @poll_changed = true if poll_parser.significantly_changes?(poll)
+      return if @poll_changed && !allow_significant_changes
 
       poll.last_fetched_at = Time.now.utc
       poll.options         = poll_parser.options
@@ -121,6 +139,8 @@ class ActivityPub::ProcessStatusUpdateService < BaseService
 
       @status.poll_id = poll.id
     elsif previous_poll.present?
+      return unless allow_significant_changes
+
       previous_poll.destroy!
       @poll_changed = true
       @status.poll_id = nil
@@ -132,7 +152,10 @@ class ActivityPub::ProcessStatusUpdateService < BaseService
     @status.spoiler_text = @status_parser.spoiler_text || ''
     @status.sensitive    = @account.sensitized? || @status_parser.sensitive || false
     @status.language     = @status_parser.language
-    @status.edited_at    = @status_parser.edited_at || Time.now.utc if significant_changes?
+
+    @significant_changes = text_significantly_changed? || @status.spoiler_text_changed? || @media_attachments_changed || @poll_changed
+
+    @status.edited_at = @status_parser.edited_at if significant_changes?
 
     @status.save!
   end
@@ -243,7 +266,14 @@ class ActivityPub::ProcessStatusUpdateService < BaseService
   end
 
   def significant_changes?
-    @status.text_changed? || @status.text_previously_changed? || @status.spoiler_text_changed? || @status.spoiler_text_previously_changed? || @media_attachments_changed || @poll_changed
+    @significant_changes
+  end
+
+  def text_significantly_changed?
+    return false unless @status.text_changed?
+
+    old, new = @status.text_change
+    HtmlAwareFormatter.new(old, false).to_s != HtmlAwareFormatter.new(new, false).to_s
   end
 
   def already_updated_more_recently?
diff --git a/app/services/remove_status_service.rb b/app/services/remove_status_service.rb
index c28e165725e..dfe9f9ac531 100644
--- a/app/services/remove_status_service.rb
+++ b/app/services/remove_status_service.rb
@@ -17,10 +17,10 @@ class RemoveStatusService < BaseService
     @account  = status.account
     @options  = options
 
-    @status.discard
-
     RedisLock.acquire(lock_options) do |lock|
       if lock.acquired?
+        @status.discard
+
         remove_from_self if @account.local?
         remove_from_followers
         remove_from_lists
diff --git a/app/views/admin/accounts/show.html.haml b/app/views/admin/accounts/show.html.haml
index 1230294fe10..a69832b046a 100644
--- a/app/views/admin/accounts/show.html.haml
+++ b/app/views/admin/accounts/show.html.haml
@@ -128,17 +128,11 @@
             %td{ rowspan: can?(:reset_password, @account.user) ? 2 : 1 }
               - if @account.user&.two_factor_enabled?
                 = t 'admin.accounts.security_measures.password_and_2fa'
-              - elsif @account.user&.skip_sign_in_token?
-                = t 'admin.accounts.security_measures.only_password'
               - else
-                = t 'admin.accounts.security_measures.password_and_sign_in_token'
+                = t 'admin.accounts.security_measures.only_password'
             %td
               - if @account.user&.two_factor_enabled?
                 = table_link_to 'unlock', t('admin.accounts.disable_two_factor_authentication'), admin_user_two_factor_authentication_path(@account.user.id), method: :delete if can?(:disable_2fa, @account.user)
-              - elsif @account.user&.skip_sign_in_token?
-                = table_link_to 'lock', t('admin.accounts.enable_sign_in_token_auth'), admin_user_sign_in_token_authentication_path(@account.user.id), method: :post if can?(:enable_sign_in_token_auth, @account.user)
-              - else
-                = table_link_to 'unlock', t('admin.accounts.disable_sign_in_token_auth'), admin_user_sign_in_token_authentication_path(@account.user.id), method: :delete if can?(:disable_sign_in_token_auth, @account.user)
 
           - if can?(:reset_password, @account.user)
             %tr
diff --git a/app/views/auth/sessions/sign_in_token.html.haml b/app/views/auth/sessions/sign_in_token.html.haml
deleted file mode 100644
index 8923203cda9..00000000000
--- a/app/views/auth/sessions/sign_in_token.html.haml
+++ /dev/null
@@ -1,14 +0,0 @@
-- content_for :page_title do
-  = t('auth.login')
-
-= simple_form_for(resource, as: resource_name, url: session_path(resource_name), method: :post) do |f|
-  %p.hint.otp-hint= t('users.suspicious_sign_in_confirmation')
-
-  .fields-group
-    = f.input :sign_in_token_attempt, type: :number, wrapper: :with_label, label: t('simple_form.labels.defaults.sign_in_token_attempt'), input_html: { 'aria-label' => t('simple_form.labels.defaults.sign_in_token_attempt'), :autocomplete => 'off' }, autofocus: true
-
-  .actions
-    = f.button :button, t('auth.login'), type: :submit
-
-  - if Setting.site_contact_email.present?
-    %p.hint.subtle-hint= t('users.generic_access_help_html', email: mail_to(Setting.site_contact_email, nil))
diff --git a/app/views/user_mailer/sign_in_token.html.haml b/app/views/user_mailer/suspicious_sign_in.html.haml
similarity index 55%
rename from app/views/user_mailer/sign_in_token.html.haml
rename to app/views/user_mailer/suspicious_sign_in.html.haml
index 826b34e7ce9..856f9fb7cf4 100644
--- a/app/views/user_mailer/sign_in_token.html.haml
+++ b/app/views/user_mailer/suspicious_sign_in.html.haml
@@ -13,32 +13,14 @@
                         %tbody
                           %tr
                             %td.column-cell.text-center.padded
-                              %table.hero-icon.alert-icon{ align: 'center', cellspacing: 0, cellpadding: 0 }
+                              %table.hero-icon.warning-icon{ align: 'center', cellspacing: 0, cellpadding: 0 }
                                 %tbody
                                   %tr
                                     %td
-                                      = image_tag full_pack_url('media/images/mailer/icon_email.png'), alt: ''
+                                      = image_tag full_pack_url('media/images/mailer/icon_lock_open.png'), alt: ''
 
-                              %h1= t 'user_mailer.sign_in_token.title'
-                              %p.lead= t 'user_mailer.sign_in_token.explanation'
-
-%table.email-table{ cellspacing: 0, cellpadding: 0 }
-  %tbody
-    %tr
-      %td.email-body
-        .email-container
-          %table.content-section{ cellspacing: 0, cellpadding: 0 }
-            %tbody
-              %tr
-                %td.content-cell.content-start
-                  %table.column{ cellspacing: 0, cellpadding: 0 }
-                    %tbody
-                      %tr
-                        %td.column-cell.input-cell
-                          %table.input{ align: 'center', cellspacing: 0, cellpadding: 0 }
-                            %tbody
-                              %tr
-                                %td= @resource.sign_in_token
+                              %h1= t 'user_mailer.suspicious_sign_in.title'
+                              %p= t 'user_mailer.suspicious_sign_in.explanation'
 
 %table.email-table{ cellspacing: 0, cellpadding: 0 }
   %tbody
@@ -55,7 +37,7 @@
                         %tbody
                           %tr
                             %td.column-cell.text-center
-                              %p= t 'user_mailer.sign_in_token.details'
+                              %p= t 'user_mailer.suspicious_sign_in.details'
                           %tr
                             %td.column-cell.text-center
                               %p
@@ -82,24 +64,4 @@
                         %tbody
                           %tr
                             %td.column-cell.text-center
-                              %p= t 'user_mailer.sign_in_token.further_actions'
-
-%table.email-table{ cellspacing: 0, cellpadding: 0 }
-  %tbody
-    %tr
-      %td.email-body
-        .email-container
-          %table.content-section{ cellspacing: 0, cellpadding: 0 }
-            %tbody
-              %tr
-                %td.content-cell
-                  %table.column{ cellspacing: 0, cellpadding: 0 }
-                    %tbody
-                      %tr
-                        %td.column-cell.button-cell
-                          %table.button{ align: 'center', cellspacing: 0, cellpadding: 0 }
-                            %tbody
-                              %tr
-                                %td.button-primary
-                                  = link_to edit_user_registration_url do
-                                    %span= t 'settings.account_settings'
+                              %p= t 'user_mailer.suspicious_sign_in.further_actions_html', action: link_to(t('user_mailer.suspicious_sign_in.change_password'), edit_user_registration_url)
diff --git a/app/views/user_mailer/sign_in_token.text.erb b/app/views/user_mailer/suspicious_sign_in.text.erb
similarity index 56%
rename from app/views/user_mailer/sign_in_token.text.erb
rename to app/views/user_mailer/suspicious_sign_in.text.erb
index 2539ddaf6da..7d2ca28e84e 100644
--- a/app/views/user_mailer/sign_in_token.text.erb
+++ b/app/views/user_mailer/suspicious_sign_in.text.erb
@@ -1,17 +1,15 @@
-<%= t 'user_mailer.sign_in_token.title' %>
+<%= t 'user_mailer.suspicious_sign_in.title' %>
 
 ===
 
-<%= t 'user_mailer.sign_in_token.explanation' %>
+<%= t 'user_mailer.suspicious_sign_in.explanation' %>
 
-=> <%= @resource.sign_in_token %>
-
-<%= t 'user_mailer.sign_in_token.details' %>
+<%= t 'user_mailer.suspicious_sign_in.details' %>
 
 <%= t('sessions.ip') %>: <%= @remote_ip %>
 <%= t('sessions.browser') %>: <%= t('sessions.description', browser: t("sessions.browsers.#{@detection.id}", default: "#{@detection.id}"), platform: t("sessions.platforms.#{@detection.platform.id}", default: "#{@detection.platform.id}")) %>
 <%= l(@timestamp) %>
 
-<%= t 'user_mailer.sign_in_token.further_actions' %>
+<%= t 'user_mailer.suspicious_sign_in.further_actions_html', action: t('user_mailer.suspicious_sign_in.change_password') %>
 
 => <%= edit_user_registration_url %>
diff --git a/config/locales/en.yml b/config/locales/en.yml
index 4a16098a81d..4fa9abc5183 100644
--- a/config/locales/en.yml
+++ b/config/locales/en.yml
@@ -199,7 +199,6 @@ en:
       security_measures:
         only_password: Only password
         password_and_2fa: Password and 2FA
-        password_and_sign_in_token: Password and e-mail token
       sensitive: Force-sensitive
       sensitized: Marked as sensitive
       shared_inbox_url: Shared inbox URL
@@ -1634,12 +1633,13 @@ en:
       explanation: You requested a full backup of your Mastodon account. It's now ready for download!
       subject: Your archive is ready for download
       title: Archive takeout
-    sign_in_token:
-      details: 'Here are details of the attempt:'
-      explanation: 'We detected an attempt to sign in to your account from an unrecognized IP address. If this is you, please enter the security code below on the sign in challenge page:'
-      further_actions: 'If this wasn''t you, please change your password and enable two-factor authentication on your account. You can do so here:'
-      subject: Please confirm attempted sign in
-      title: Sign in attempt
+    suspicious_sign_in:
+      change_password: change your password
+      details: 'Here are details of the sign-in:'
+      explanation: We've detected a sign-in to your account from a new IP address.
+      further_actions_html: If this wasn't you, we recommend that you %{action} immediately and enable two-factor authentication to keep your account secure.
+      subject: Your account has been accessed from a new IP address
+      title: A new sign-in
     warning:
       appeal: Submit an appeal
       appeal_description: If you believe this is an error, you can submit an appeal to the staff of %{instance}.
@@ -1690,13 +1690,10 @@ en:
       title: Welcome aboard, %{name}!
   users:
     follow_limit_reached: You cannot follow more than %{limit} people
-    generic_access_help_html: Trouble accessing your account? You may get in touch with %{email} for assistance
     invalid_otp_token: Invalid two-factor code
-    invalid_sign_in_token: Invalid security code
     otp_lost_help_html: If you lost access to both, you may get in touch with %{email}
     seamless_external_login: You are logged in via an external service, so password and e-mail settings are not available.
     signed_in_as: 'Signed in as:'
-    suspicious_sign_in_confirmation: You appear to not have logged in from this device before, so we're sending a security code to your e-mail address to confirm that it's you.
   verification:
     explanation_html: 'You can <strong>verify yourself as the owner of the links in your profile metadata</strong>. For that, the linked website must contain a link back to your Mastodon profile. The link back <strong>must</strong> have a <code>rel="me"</code> attribute. The text content of the link does not matter. Here is an example:'
     verification: Verification
diff --git a/config/routes.rb b/config/routes.rb
index 55e17ab14cb..5747157057f 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -298,7 +298,6 @@ Rails.application.routes.draw do
 
     resources :users, only: [] do
       resource :two_factor_authentication, only: [:destroy]
-      resource :sign_in_token_authentication, only: [:create, :destroy]
     end
 
     resources :custom_emojis, only: [:index, :new, :create] do
diff --git a/lib/mastodon/accounts_cli.rb b/lib/mastodon/accounts_cli.rb
index 2ef85d0a91c..7256d1da98f 100644
--- a/lib/mastodon/accounts_cli.rb
+++ b/lib/mastodon/accounts_cli.rb
@@ -55,7 +55,6 @@ module Mastodon
     option :email, required: true
     option :confirmed, type: :boolean
     option :role, default: 'user', enum: %w(user moderator admin)
-    option :skip_sign_in_token, type: :boolean
     option :reattach, type: :boolean
     option :force, type: :boolean
     desc 'create USERNAME', 'Create a new user'
@@ -69,9 +68,6 @@ module Mastodon
       With the --role option one of  "user", "admin" or "moderator"
       can be supplied. Defaults to "user"
 
-      With the --skip-sign-in-token option, you can ensure that
-      the user is never asked for an e-mailed security code.
-
       With the --reattach option, the new user will be reattached
       to a given existing username of an old account. If the old
       account is still in use by someone else, you can supply
@@ -81,7 +77,7 @@ module Mastodon
     def create(username)
       account  = Account.new(username: username)
       password = SecureRandom.hex
-      user     = User.new(email: options[:email], password: password, agreement: true, approved: true, admin: options[:role] == 'admin', moderator: options[:role] == 'moderator', confirmed_at: options[:confirmed] ? Time.now.utc : nil, bypass_invite_request_check: true, skip_sign_in_token: options[:skip_sign_in_token])
+      user     = User.new(email: options[:email], password: password, agreement: true, approved: true, admin: options[:role] == 'admin', moderator: options[:role] == 'moderator', confirmed_at: options[:confirmed] ? Time.now.utc : nil, bypass_invite_request_check: true)
 
       if options[:reattach]
         account = Account.find_local(username) || Account.new(username: username)
@@ -125,7 +121,6 @@ module Mastodon
     option :disable_2fa, type: :boolean
     option :approve, type: :boolean
     option :reset_password, type: :boolean
-    option :skip_sign_in_token, type: :boolean
     desc 'modify USERNAME', 'Modify a user'
     long_desc <<-LONG_DESC
       Modify a user account.
@@ -147,9 +142,6 @@ module Mastodon
 
       With the --reset-password option, the user's password is replaced by
       a randomly-generated one, printed in the output.
-
-      With the --skip-sign-in-token option, you can ensure that
-      the user is never asked for an e-mailed security code.
     LONG_DESC
     def modify(username)
       user = Account.find_local(username)&.user
@@ -171,7 +163,6 @@ module Mastodon
       user.disabled = true if options[:disable]
       user.approved = true if options[:approve]
       user.otp_required_for_login = false if options[:disable_2fa]
-      user.skip_sign_in_token = options[:skip_sign_in_token] unless options[:skip_sign_in_token].nil?
       user.confirm if options[:confirm]
 
       if user.save
diff --git a/spec/controllers/auth/sessions_controller_spec.rb b/spec/controllers/auth/sessions_controller_spec.rb
index 64ec7b79463..1b8fd0b7b0a 100644
--- a/spec/controllers/auth/sessions_controller_spec.rb
+++ b/spec/controllers/auth/sessions_controller_spec.rb
@@ -225,22 +225,6 @@ RSpec.describe Auth::SessionsController, type: :controller do
           end
         end
 
-        context 'using email and password after an unfinished log-in attempt with a sign-in token challenge' do
-          let!(:other_user) do
-            Fabricate(:user, email: 'z@y.com', password: 'abcdefgh', otp_required_for_login: false, current_sign_in_at: 1.month.ago)
-          end
-
-          before do
-            post :create, params: { user: { email: other_user.email, password: other_user.password } }
-            post :create, params: { user: { email: user.email, password: user.password } }
-          end
-
-          it 'renders two factor authentication page' do
-            expect(controller).to render_template("two_factor")
-            expect(controller).to render_template(partial: "_otp_authentication_form")
-          end
-        end
-
         context 'using upcase email and password' do
           before do
             post :create, params: { user: { email: user.email.upcase, password: user.password } }
@@ -266,21 +250,6 @@ RSpec.describe Auth::SessionsController, type: :controller do
           end
         end
 
-        context 'using a valid OTP, attempting to leverage previous half-login to bypass password auth' do
-          let!(:other_user) do
-            Fabricate(:user, email: 'z@y.com', password: 'abcdefgh', otp_required_for_login: false, current_sign_in_at: 1.month.ago)
-          end
-
-          before do
-            post :create, params: { user: { email: other_user.email, password: other_user.password } }
-            post :create, params: { user: { email: user.email, otp_attempt: user.current_otp } }, session: { attempt_user_updated_at: user.updated_at.to_s }
-          end
-
-          it "doesn't log the user in" do
-            expect(controller.current_user).to be_nil
-          end
-        end
-
         context 'when the server has an decryption error' do
           before do
             allow_any_instance_of(User).to receive(:validate_and_consume_otp!).and_raise(OpenSSL::Cipher::CipherError)
@@ -401,126 +370,6 @@ RSpec.describe Auth::SessionsController, type: :controller do
         end
       end
     end
-
-    context 'when 2FA is disabled and IP is unfamiliar' do
-      let!(:user) { Fabricate(:user, email: 'x@y.com', password: 'abcdefgh', current_sign_in_at: 3.weeks.ago) }
-
-      before do
-        request.remote_ip  = '10.10.10.10'
-        request.user_agent = 'Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:75.0) Gecko/20100101 Firefox/75.0'
-
-        allow(UserMailer).to receive(:sign_in_token).and_return(double('email', deliver_later!: nil))
-      end
-
-      context 'using email and password' do
-        before do
-          post :create, params: { user: { email: user.email, password: user.password } }
-        end
-
-        it 'renders sign in token authentication page' do
-          expect(controller).to render_template("sign_in_token")
-        end
-
-        it 'generates sign in token' do
-          expect(user.reload.sign_in_token).to_not be_nil
-        end
-
-        it 'sends sign in token e-mail' do
-          expect(UserMailer).to have_received(:sign_in_token)
-        end
-      end
-
-      context 'using email and password after an unfinished log-in attempt to a 2FA-protected account' do
-        let!(:other_user) do
-          Fabricate(:user, email: 'z@y.com', password: 'abcdefgh', otp_required_for_login: true, otp_secret: User.generate_otp_secret(32))
-        end
-
-        before do
-          post :create, params: { user: { email: other_user.email, password: other_user.password } }
-          post :create, params: { user: { email: user.email, password: user.password } }
-        end
-
-        it 'renders sign in token authentication page' do
-          expect(controller).to render_template("sign_in_token")
-        end
-
-        it 'generates sign in token' do
-          expect(user.reload.sign_in_token).to_not be_nil
-        end
-
-        it 'sends sign in token e-mail' do
-          expect(UserMailer).to have_received(:sign_in_token)
-        end
-      end
-
-      context 'using email and password after an unfinished log-in attempt with a sign-in token challenge' do
-        let!(:other_user) do
-          Fabricate(:user, email: 'z@y.com', password: 'abcdefgh', otp_required_for_login: false, current_sign_in_at: 1.month.ago)
-        end
-
-        before do
-          post :create, params: { user: { email: other_user.email, password: other_user.password } }
-          post :create, params: { user: { email: user.email, password: user.password } }
-        end
-
-        it 'renders sign in token authentication page' do
-          expect(controller).to render_template("sign_in_token")
-        end
-
-        it 'generates sign in token' do
-          expect(user.reload.sign_in_token).to_not be_nil
-        end
-
-        it 'sends sign in token e-mail' do
-          expect(UserMailer).to have_received(:sign_in_token).with(user, any_args)
-        end
-      end
-
-      context 'using a valid sign in token' do
-        before do
-          user.generate_sign_in_token && user.save
-          post :create, params: { user: { sign_in_token_attempt: user.sign_in_token } }, session: { attempt_user_id: user.id, attempt_user_updated_at: user.updated_at.to_s }
-        end
-
-        it 'redirects to home' do
-          expect(response).to redirect_to(root_path)
-        end
-
-        it 'logs the user in' do
-          expect(controller.current_user).to eq user
-        end
-      end
-
-      context 'using a valid sign in token, attempting to leverage previous half-login to bypass password auth' do
-        let!(:other_user) do
-          Fabricate(:user, email: 'z@y.com', password: 'abcdefgh', otp_required_for_login: false, current_sign_in_at: 1.month.ago)
-        end
-
-        before do
-          user.generate_sign_in_token && user.save
-          post :create, params: { user: { email: other_user.email, password: other_user.password } }
-          post :create, params: { user: { email: user.email, sign_in_token_attempt: user.sign_in_token } }, session: { attempt_user_updated_at: user.updated_at.to_s }
-        end
-
-        it "doesn't log the user in" do
-          expect(controller.current_user).to be_nil
-        end
-      end
-
-      context 'using an invalid sign in token' do
-        before do
-          post :create, params: { user: { sign_in_token_attempt: 'wrongotp' } }, session: { attempt_user_id: user.id, attempt_user_updated_at: user.updated_at.to_s }
-        end
-
-        it 'shows a login error' do
-          expect(flash[:alert]).to match I18n.t('users.invalid_sign_in_token')
-        end
-
-        it "doesn't log the user in" do
-          expect(controller.current_user).to be_nil
-        end
-      end
-    end
   end
 
   describe 'GET #webauthn_options' do
diff --git a/spec/lib/suspicious_sign_in_detector_spec.rb b/spec/lib/suspicious_sign_in_detector_spec.rb
new file mode 100644
index 00000000000..101a18aa017
--- /dev/null
+++ b/spec/lib/suspicious_sign_in_detector_spec.rb
@@ -0,0 +1,57 @@
+require 'rails_helper'
+
+RSpec.describe SuspiciousSignInDetector do
+  describe '#suspicious?' do
+    let(:user) { Fabricate(:user, current_sign_in_at: 1.day.ago) }
+    let(:request) { double(remote_ip: remote_ip) }
+    let(:remote_ip) { nil }
+
+    subject { described_class.new(user).suspicious?(request) }
+
+    context 'when user has 2FA enabled' do
+      before do
+        user.update!(otp_required_for_login: true)
+      end
+
+      it 'returns false' do
+        expect(subject).to be false
+      end
+    end
+
+    context 'when exact IP has been used before' do
+      let(:remote_ip) { '1.1.1.1' }
+
+      before do
+        user.update!(sign_up_ip: remote_ip)
+      end
+
+      it 'returns false' do
+        expect(subject).to be false
+      end
+    end
+
+    context 'when similar IP has been used before' do
+      let(:remote_ip) { '1.1.2.2' }
+
+      before do
+        user.update!(sign_up_ip: '1.1.1.1')
+      end
+
+      it 'returns false' do
+        expect(subject).to be false
+      end
+    end
+
+    context 'when IP is completely unfamiliar' do
+      let(:remote_ip) { '2.2.2.2' }
+
+      before do
+        user.update!(sign_up_ip: '1.1.1.1')
+      end
+
+      it 'returns true' do
+        expect(subject).to be true
+      end
+    end
+  end
+end
diff --git a/spec/mailers/previews/user_mailer_preview.rb b/spec/mailers/previews/user_mailer_preview.rb
index 8de7d866967..95712e6cf42 100644
--- a/spec/mailers/previews/user_mailer_preview.rb
+++ b/spec/mailers/previews/user_mailer_preview.rb
@@ -87,8 +87,8 @@ class UserMailerPreview < ActionMailer::Preview
     UserMailer.appeal_approved(User.first, Appeal.last)
   end
 
-  # Preview this email at http://localhost:3000/rails/mailers/user_mailer/sign_in_token
-  def sign_in_token
-    UserMailer.sign_in_token(User.first.tap { |user| user.generate_sign_in_token }, '127.0.0.1', 'Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:75.0) Gecko/20100101 Firefox/75.0', Time.now.utc)
+  # Preview this email at http://localhost:3000/rails/mailers/user_mailer/suspicious_sign_in
+  def suspicious_sign_in
+    UserMailer.suspicious_sign_in(User.first, '127.0.0.1', 'Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:75.0) Gecko/20100101 Firefox/75.0', Time.now.utc)
   end
 end
diff --git a/spec/services/activitypub/fetch_remote_status_service_spec.rb b/spec/services/activitypub/fetch_remote_status_service_spec.rb
index 68816e55476..943cb161d78 100644
--- a/spec/services/activitypub/fetch_remote_status_service_spec.rb
+++ b/spec/services/activitypub/fetch_remote_status_service_spec.rb
@@ -195,7 +195,7 @@ RSpec.describe ActivityPub::FetchRemoteStatusService, type: :service do
       let(:existing_status) { Fabricate(:status, account: sender, text: 'Foo', uri: note[:id]) }
 
       context 'with a Note object' do
-        let(:object) { note }
+        let(:object) { note.merge(updated: '2021-09-08T22:39:25Z') }
 
         it 'updates status' do
           existing_status.reload
@@ -211,7 +211,7 @@ RSpec.describe ActivityPub::FetchRemoteStatusService, type: :service do
             id: "https://#{valid_domain}/@foo/1234/create",
             type: 'Create',
             actor: ActivityPub::TagManager.instance.uri_for(sender),
-            object: note,
+            object: note.merge(updated: '2021-09-08T22:39:25Z'),
           }
         end
 
diff --git a/spec/services/activitypub/process_status_update_service_spec.rb b/spec/services/activitypub/process_status_update_service_spec.rb
index f87adcae137..481572742b3 100644
--- a/spec/services/activitypub/process_status_update_service_spec.rb
+++ b/spec/services/activitypub/process_status_update_service_spec.rb
@@ -1,5 +1,9 @@
 require 'rails_helper'
 
+def poll_option_json(name, votes)
+  { type: 'Note', name: name, replies: { type: 'Collection', totalItems: votes } }
+end
+
 RSpec.describe ActivityPub::ProcessStatusUpdateService, type: :service do
   let!(:status) { Fabricate(:status, text: 'Hello world', account: Fabricate(:account, domain: 'example.com')) }
 
@@ -46,6 +50,180 @@ RSpec.describe ActivityPub::ProcessStatusUpdateService, type: :service do
       expect(status.reload.spoiler_text).to eq 'Show more'
     end
 
+    context 'when the changes are only in sanitized-out HTML' do
+      let!(:status) { Fabricate(:status, text: '<p>Hello world <a href="https://joinmastodon.org" rel="nofollow">joinmastodon.org</a></p>', account: Fabricate(:account, domain: 'example.com')) }
+
+      let(:payload) do
+        {
+          '@context': 'https://www.w3.org/ns/activitystreams',
+          id: 'foo',
+          type: 'Note',
+          updated: '2021-09-08T22:39:25Z',
+          content: '<p>Hello world <a href="https://joinmastodon.org" rel="noreferrer">joinmastodon.org</a></p>',
+        }
+      end
+
+      before do
+        subject.call(status, json)
+      end
+
+      it 'does not create any edits' do
+        expect(status.reload.edits).to be_empty
+      end
+
+      it 'does not mark status as edited' do
+        expect(status.edited?).to be false
+      end
+    end
+
+    context 'when the status has not been explicitly edited' do
+      let(:payload) do
+        {
+          '@context': 'https://www.w3.org/ns/activitystreams',
+          id: 'foo',
+          type: 'Note',
+          content: 'Updated text',
+        }
+      end
+
+      before do
+        subject.call(status, json)
+      end
+
+      it 'does not create any edits' do
+        expect(status.reload.edits).to be_empty
+      end
+
+      it 'does not mark status as edited' do
+        expect(status.reload.edited?).to be false
+      end
+
+      it 'does not update the text' do
+        expect(status.reload.text).to eq 'Hello world'
+      end
+    end
+
+    context 'when the status has not been explicitly edited and features a poll' do
+      let(:account)    { Fabricate(:account, domain: 'example.com') }
+      let!(:expiration) { 10.days.from_now.utc }
+      let!(:status) do
+        Fabricate(:status,
+          text: 'Hello world',
+          account: account,
+          poll_attributes: {
+            options: %w(Foo Bar),
+            account: account,
+            multiple: false,
+            hide_totals: false,
+            expires_at: expiration
+          }
+        )
+      end
+
+      let(:payload) do
+        {
+          '@context': 'https://www.w3.org/ns/activitystreams',
+          id: 'https://example.com/foo',
+          type: 'Question',
+          content: 'Hello world',
+          endTime: expiration.iso8601,
+          oneOf: [
+            poll_option_json('Foo', 4),
+            poll_option_json('Bar', 3),
+          ],
+        }
+      end
+
+      before do
+        subject.call(status, json)
+      end
+
+      it 'does not create any edits' do
+        expect(status.reload.edits).to be_empty
+      end
+
+      it 'does not mark status as edited' do
+        expect(status.reload.edited?).to be false
+      end
+
+      it 'does not update the text' do
+        expect(status.reload.text).to eq 'Hello world'
+      end
+
+      it 'updates tallies' do
+        expect(status.poll.reload.cached_tallies).to eq [4, 3]
+      end
+    end
+
+    context 'when the status changes a poll despite being not explicitly marked as updated' do
+      let(:account)    { Fabricate(:account, domain: 'example.com') }
+      let!(:expiration) { 10.days.from_now.utc }
+      let!(:status) do
+        Fabricate(:status,
+          text: 'Hello world',
+          account: account,
+          poll_attributes: {
+            options: %w(Foo Bar),
+            account: account,
+            multiple: false,
+            hide_totals: false,
+            expires_at: expiration
+          }
+        )
+      end
+
+      let(:payload) do
+        {
+          '@context': 'https://www.w3.org/ns/activitystreams',
+          id: 'https://example.com/foo',
+          type: 'Question',
+          content: 'Hello world',
+          endTime: expiration.iso8601,
+          oneOf: [
+            poll_option_json('Foo', 4),
+            poll_option_json('Bar', 3),
+            poll_option_json('Baz', 3),
+          ],
+        }
+      end
+
+      before do
+        subject.call(status, json)
+      end
+
+      it 'does not create any edits' do
+        expect(status.reload.edits).to be_empty
+      end
+
+      it 'does not mark status as edited' do
+        expect(status.reload.edited?).to be false
+      end
+
+      it 'does not update the text' do
+        expect(status.reload.text).to eq 'Hello world'
+      end
+
+      it 'does not update tallies' do
+        expect(status.poll.reload.cached_tallies).to eq [0, 0]
+      end
+    end
+
+    context 'when receiving an edit older than the latest processed' do
+      before do
+        status.snapshot!(at_time: status.created_at, rate_limit: false)
+        status.update!(text: 'Hello newer world', edited_at: Time.now.utc)
+        status.snapshot!(rate_limit: false)
+      end
+
+      it 'does not create any edits' do
+        expect { subject.call(status, json) }.not_to change { status.reload.edits.pluck(&:id) }
+      end
+
+      it 'does not update the text, spoiler_text or edited_at' do
+        expect { subject.call(status, json) }.not_to change { s = status.reload; [s.text, s.spoiler_text, s.edited_at] }
+      end
+    end
+
     context 'with no changes at all' do
       let(:payload) do
         {