Android 14 and especially Pixel devices frequently stop activities for performance reasons (mostly overnight).

If the activity is restarted by Android OS, the PopupStack still contains visible popups although the DecorView of the restored activity is empty (if popups were visible before activity disposal).

I assume that MopupService is not expecting or capturing the disposal of the main activity.

Apparently, Maui has its troubles with this case as the App methods (OnStart, OnResume) are not called when Android restarts the activity. Maybe this is somehow related.
dotnet/maui#18845