This sample app is used to show that the AudioMode works different on different verisons of Android.

What I see on Android 11+ is that when I enable Bluetooth SCO, and set AudioManager to mode MODE_IN_COMMUNICATION, something is switching the mode back to MODE_NORMAL. The problem with this mode changing, if I pair this with logic that needs to use the microphone, as soon as the mode changes, the microphone and the TTS no longer work on the BT headset.

Android 10 - Using a Honeyewell CT40. The AudioMode never changes. It is running Android 10 Kernal Version 4.14.163-perf+ #1 Fri Aug 13 11:11:29 HKT 2021

Android 11 - I have used a Zebra TC52. This one shows that the AudioMode changes often regardless of if TTS is speaking or not.

Android 12 - I have used a Pixel 4. It acts the same as the Android 11 device.