Try hard reset (long press (~15s) both buttons).

I know I have had this issue and did not have it after reset. Though I do have another annoying, and seemingly unique issue: sometimes, when adjusting the position of the headphone, they do a “click” (and a loud one), and just shut down. After a few seconds, they boot up again.

The farthest from the last reset, the more often it happens. I have no idea why.