Sorry for the long time without answser, many other projects to work on.
I just tried the file with an old LG G3 running Android 5.0, with a basic app build with unity 2020.2.1f1.
I had no OnApplicationPause problem when i go back to the app after pausing (I tried many ways to pause and go back for 5 minutes).
Without this file, the bug was still here.
It looks like its working!