AudioSession is deactivated occasionally in app background in iOS 14.2 when using AirPods

I'm writing a VoIP app and my audio session config is:

category: PlayAndRecord
mode: VoiceChat
categoryOptions: AllowBluetooth | AllowBluetoothA2DP | MixWithOthers | DuckOthers | AllowAirPlay

The audio works fine under normal circumstances. But when use bluetooth devices(Airpods) and go to the background(or lock the screen), my audio stops occasionally(very rare) and i find that my audio session is NOT active. It seems like the UIBackgroundMode configuration is not working?

Before the deactivation there's only a routeChangeNotification: categoryChange, without any other notifications like interrupt.

Once the case happens, it keeps going whenever i reconfigure and restart my audio session, unless i reinstall the app.

The case happens in iOS 14.2, at least not yet in other systems.

I have no idea why it happens, does anyone know about this issue?
AudioSession is deactivated occasionally in app background in iOS 14.2 when using AirPods
 
 
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