Same problem with iPhone XSmax (probably not relevant) and ios 15.7.
playing to Bluetooth speakers. Plays and occasionally just randomly stops paying. The phone still “to thinks it’s playing “ (ie the pause button is displayed as the control on the music app) but no audio. Occurred in the past 4-5 months. I’m assuming apple broke something in the audio Subsystem.
its the basic Gen 1 core feature that apple cannot seem to keep working that are so frustrating. Playing music from files on the phone , reminders list to the watch (v2) , simpel stuff broken by updates.