I’m developing a multi-user turn-based word game in Flutter which uses FCM topics to notify players of moves done.

I’ve now published a version on Google Play for internal testing and the delays between sending and receiving messages are often well over 10 seconds. This was not the case when developing and using emulators. Then again, I’m also using a newer version of Flutter (3.22) and the firebase_messaging package, so that could also be the reason.

Why is the delay so high and is there anything I can do to remedy this? Delays up to a couple of seconds are acceptable, but not more.
The sending of the messages from Firebase is requested from a node backend using the firebase-admin package.