Hi team, We've observed that for all background notifications (where content-available set to true, https://developer.apple.com/documentation/usernotifications/pushing-background-updates-to-your-app#Create-a-background-notification), we never received any response with error string "Unregistered". This differs from non-background pushes, where expired tokens are regularly cleared. Is this the expected behavior (i.e., background notifications will not return an "Unregistered" error), or could this indicate an issue on our side? Thanks in advance for any clarification.