This experience of different devices competing for a BT headphone is really the most annoying aspect of BT to me. I pair my headphones regularly with my work laptop, my phone and my private laptop, and when working from home and walking around in my apartment, the headphones sometimes just randomly pick another device, even if the current device has audio going, and the other does nothing. Sometimes the Macbook does that when it's on standby, which is bizarre. I always wondered if that is an implementation bug on one of the sides. I fixed it by forcing the Macbook to shut off BT when going on standby.