Ensure that you have the latest version of Slowly installed. If you are already using the latest version and notifications still aren't working, consider reinstalling the app. This action forces a refresh of the endpoint token, which can resolve notification issues.
Please be aware that Slowly's notifications are mostly scheduled, so there might be a delay between the time a notification is sent and when it is received. Even after completing the above steps, you may not receive scheduled notifications that were sent before the fix. Please allow up to 1-2 days for all notifications to return to normal.