Same issue to me.
@Miki @Ahmet Burak please can you reply to @andrewilley?
@andrewilley I think bluetooth breakdown is specific to that devices (cars) for all apps (not for all devices - car), as it does for me too.
Poweramp Full build 939
Oneplus 3T
Oxygen OS 9.0.6 (Android 9)
Ford Fiesta m.y. 2018
As a workaround to connection breakdown, I disabled the Poweramp service and notification keeping, so I can use my smartphone bluetooth in my car with other apps without uninstalling Poweramp.
I just reverted to AVRCP 1.3 and disabled 'No dvc for absolute volume’ option. I will try. Thanks.