! I hope I can help. I've been struggling with this problem for years and I've tried everything I could read on the forums. Nothing helped, and then I thought that there might be something wrong with the bluetooth headphones... and yes, that's what happened. Even though I set all inputs to 48Khz, if I connected or even connected one of the three AirPods (gen2, Pro gen1, Max) by itself, the sound deteriorated over time. If you look, for example, the microphone of the Airpods Max takes 24Khz for some reason and cannot be adjusted. The bottom line is that the solution was to completely turn off bluetooth on the MacBook and thus not give the headphones a chance to connect.