Do these relaxed rules for the delivery of silent push notifications also apply to TestFlight builds? I have been testing on a few different devices, but I'm seeing inconsistent results. On one device, the silent pushes are able to successfully launch my app in the background, even after the app has been force killed by the user. This had me hopeful that I could get this working for all app states (foreground, background, killed).

I also noticed that OP forgot to include the "apns-push-type" header field that is described in the developer docs. Maybe that was added later. "Additionally, the notification’s POST request should contain the apns-push-type header field with a value of background, and the apns-priority field with a value of 5."

Yes, I was opening the app switcher and swiping my app away to force quit. Then using a cloud function to deliver FCM background pushes, which would then launch my app in the background (not visible to the user). I'm not building this natively though, but using a cross-platform React Native library so it abstracts away some of the implementation details. The docs claim to support handling messages in background/quit states. https://rnfirebase.io/messaging/usage#background-application-state

Thanks for the clarification. Could OP use something like iBeacon region monitoring to wake up the app from a killed state?