diff --git a/app/models/group_user.rb b/app/models/group_user.rb
index 5ee988eaa70..5e6b3f7dcba 100644
--- a/app/models/group_user.rb
+++ b/app/models/group_user.rb
@@ -120,7 +120,7 @@ class GroupUser < ActiveRecord::Base
     return if group.grant_trust_level.nil?
     return if self.destroyed_by_association&.active_record == User # User is being destroyed, so don't try to recalculate
 
-    Promotion.recalculate(user)
+    Promotion.recalculate(user, use_previous_trust_level: true)
   end
 
   def set_category_notifications
diff --git a/app/services/staff_action_logger.rb b/app/services/staff_action_logger.rb
index f5c3386f15e..a4203452bb7 100644
--- a/app/services/staff_action_logger.rb
+++ b/app/services/staff_action_logger.rb
@@ -100,7 +100,8 @@ class StaffActionLogger
     UserHistory.create!(params(opts).merge(
       action: UserHistory.actions[:change_trust_level],
       target_user_id: user.id,
-      details: "old trust level: #{old_trust_level}\nnew trust level: #{new_trust_level}"
+      previous_value: old_trust_level,
+      new_value: new_trust_level,
     ))
   end
 
diff --git a/db/migrate/20220818171849_move_tl_user_history_to_previous_and_new_value.rb b/db/migrate/20220818171849_move_tl_user_history_to_previous_and_new_value.rb
new file mode 100644
index 00000000000..6bd3022c8c5
--- /dev/null
+++ b/db/migrate/20220818171849_move_tl_user_history_to_previous_and_new_value.rb
@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+
+class MoveTlUserHistoryToPreviousAndNewValue < ActiveRecord::Migration[7.0]
+  def change
+    execute <<~SQL
+      UPDATE user_histories
+      SET previous_value = old_tl,
+          new_value = new_tl,
+          details = NULL
+      FROM (
+          SELECT id user_history_id,
+                 (REGEXP_MATCHES(details, 'old trust level: (\d+)', 'i'))[1] old_tl,
+                 (REGEXP_MATCHES(details, 'new trust level: (\d+)', 'i'))[1] new_tl
+          FROM user_histories
+          WHERE action = 2
+      ) trust_levels
+      WHERE user_histories.id = trust_levels.user_history_id
+    SQL
+  end
+end
diff --git a/lib/promotion.rb b/lib/promotion.rb
index 5ac5ee519da..da0f89916fa 100644
--- a/lib/promotion.rb
+++ b/lib/promotion.rb
@@ -121,21 +121,12 @@ class Promotion
   end
 
   # Figure out what a user's trust level should be from scratch
-  def self.recalculate(user, performed_by = nil)
-    # First, use the manual locked level
-    unless user.manual_locked_trust_level.nil?
-      return user.update!(
-        trust_level: user.manual_locked_trust_level
-      )
-    end
-
-    # Then consider the group locked level
-    user_group_granted_trust_level = user.group_granted_trust_level
-
-    if user_group_granted_trust_level.present?
-      return user.update(
-        trust_level: user_group_granted_trust_level
-      )
+  def self.recalculate(user, performed_by = nil, use_previous_trust_level: false)
+    granted_trust_level = TrustLevel.calculate(
+      user, use_previous_trust_level: use_previous_trust_level
+    )
+    if granted_trust_level.present?
+      return user.update(trust_level: granted_trust_level)
     end
 
     user.update_column(:trust_level, TrustLevel[0])
diff --git a/lib/trust_level.rb b/lib/trust_level.rb
index 8c87c9ac1e3..b776056b7aa 100644
--- a/lib/trust_level.rb
+++ b/lib/trust_level.rb
@@ -3,33 +3,51 @@
 class InvalidTrustLevel < StandardError; end
 
 class TrustLevel
+  def self.[](level)
+    raise InvalidTrustLevel if !valid?(level)
 
-  class << self
-
-    def [](level)
-      raise InvalidTrustLevel if !valid?(level)
-      level
-    end
-
-    def levels
-      @levels ||= Enum.new(:newuser, :basic, :member, :regular, :leader, start: 0)
-    end
-
-    def valid?(level)
-      valid_range === level
-    end
-
-    def valid_range
-      (0..4)
-    end
-
-    def compare(current_level, level)
-      (current_level || 0) >= level
-    end
-
-    def name(level)
-      I18n.t("js.trust_levels.names.#{levels[level]}")
-    end
+    level
   end
 
+  def self.levels
+    @levels ||= Enum.new(:newuser, :basic, :member, :regular, :leader, start: 0)
+  end
+
+  def self.valid?(level)
+    valid_range === level
+  end
+
+  def self.valid_range
+    (0..4)
+  end
+
+  def self.compare(current_level, level)
+    (current_level || 0) >= level
+  end
+
+  def self.name(level)
+    I18n.t("js.trust_levels.names.#{levels[level]}")
+  end
+
+  def self.calculate(user, use_previous_trust_level: false)
+    # First, use the manual locked level
+    return user.manual_locked_trust_level if user.manual_locked_trust_level.present?
+
+    # Then consider the group locked level (or the previous trust level)
+    granted_trust_level = user.group_granted_trust_level || 0
+    previous_trust_level = use_previous_trust_level ? find_previous_trust_level(user) : 0
+
+    [granted_trust_level, previous_trust_level].max
+  end
+
+  private
+
+  def self.find_previous_trust_level(user)
+    UserHistory
+      .where(action: UserHistory.actions[:change_trust_level])
+      .where(target_user_id: user.id)
+      .order(created_at: :desc)
+      .pluck_first(:new_value)
+      .to_i
+  end
 end
diff --git a/spec/models/group_user_spec.rb b/spec/models/group_user_spec.rb
index 16b9404b1e7..5fe790dc5fb 100644
--- a/spec/models/group_user_spec.rb
+++ b/spec/models/group_user_spec.rb
@@ -237,5 +237,20 @@ RSpec.describe GroupUser do
       expect(user.primary_group_id).to be_nil
       expect(user.flair_group_id).to be_nil
     end
+
+    it "restores previous trust level" do
+      user = Fabricate(:user)
+      expect(user.trust_level).to eq(1)
+
+      user.change_trust_level!(2, log_action_for: Discourse.system_user)
+      user.change_trust_level!(3, log_action_for: Discourse.system_user)
+      group.update!(grant_trust_level: 4)
+
+      group_user = Fabricate(:group_user, group: group, user: user)
+      expect(user.reload.trust_level).to eq(4)
+
+      group_user.destroy!
+      expect(user.reload.trust_level).to eq(3)
+    end
   end
 end
diff --git a/spec/services/staff_action_logger_spec.rb b/spec/services/staff_action_logger_spec.rb
index a5bfaef522e..b448bb0230f 100644
--- a/spec/services/staff_action_logger_spec.rb
+++ b/spec/services/staff_action_logger_spec.rb
@@ -132,7 +132,8 @@ RSpec.describe StaffActionLogger do
 
     it 'creates a new UserHistory record' do
       expect { log_trust_level_change }.to change { UserHistory.count }.by(1)
-      expect(UserHistory.last.details).to include "new trust level: #{new_trust_level}"
+      expect(UserHistory.last.previous_value).to eq(old_trust_level.to_s)
+      expect(UserHistory.last.new_value).to eq(new_trust_level.to_s)
     end
   end