boilermakerThere are already other threads about this issue. It is the single most annoying thing about this phone in my use case. almost all calls are interrupted by the person on the other side asking if i'm still here, because of the face to mute button touch
Somewhat related, I've found the proximity sensor to be extremely buggy without headphones (holding phone to head). Constantly knock the mute button and if I try to use the phone during a call (while on speaker), the screen turns off (proximity sensor activation).