GrapheneOS For apps using FCM, you need Unrestricted battery mode for Play services
I just checked "Play Services" (Unrestricted Battery) . I think is the default configuration.
GrapheneOS For apps using their own background push service, you need Unrestricted battery mode for the app
Yes, for example Tutanota uses its own push system, so after installing it the Unrestricted battery mode was selected as recommended by the application developer.
GrapheneOS Apps doing their own push need to run a foreground service which must create a non-hidden persistent notification which the user can disable without breaking it. It will show up in active apps when the service is running, so you can see when it's running the push service.
Yes, I remember seeing it before in a messaging application called conversations, a chain icon is showed in top bar.
GrapheneOS There's no indication of any GrapheneOS issue for any of this. It's almost certainly a configuration issue with your device. You haven't said anything about your battery optimization configuration for Play services or apps doing their own push. All the apps you listed likely using FCM via Play services for push when it's available, and some of them will do their own push when it's not available. Their decision about using their own push may be done statically on first launch after install or app data reset rather than dynamically at each app launch. It depends on how the app chose to do it.
As I said in the previous paragraph, Play Services battery optimization is properly set (Unrestricted Battery) and Tutanota too. Of course Signal is using FCM so i keept (Optimization battery).
Tutanota -> Run notification service in foreground (random fails with unrestricted battery
Signal -> Runs FCM (random fails)
Whatsapp -> Runs FCM (random fails)
GrapheneOS It's almost certainly a configuration issue with your device
Agree, if only two people have that error, it is the most logical thing.
Thx