DAC DISCONNECT IN BACKGROUND, SOLVED!
Listening music via DAC USB C with background apps closed, the screen turned off, and the phone in your pocket (it only happens with your phone in your pocket) the audio connection (but not power) disconnects (as if we unplug your headphones from the DAC) with random timing. After endless tests I solved by disabling OPTIFLEX and setting the battery setting on messaging apps to unrestricted (Whatsapp in my case). This will lead to a negligible greater use of the battery. I hope I was helpful.