app/services/mastodon_manager/sync_account_profiles.rb

@@ -24,7 +24,7 @@ module MastodonManager
           mastodon_user = MastodonManager::FindUser.call username: user.cn
           if mastodon_user
             Rails.logger.debug { "Setting mastodon_id for user #{user.cn}" }
-            user.update! mastodon_id: mastodon_user.dig(:account, :id).to_i
+            user.update! mastodon_id: @user[:id]
           else
             Rails.logger.debug { "No Mastodon user found for username #{user.cn}" }
             next