These actions mute the microphone:

• MediaSettings in call: changing the camera/mic hardware
• BottomBar in call: changing the camera/mic hardware

Most likely comes from assumption, that when we're in the call opening device checker, microphone and camera should be disabled on change, as you might want to try different devices before applying settings. That shouldn't work the same way in BottomBar

Originally posted by @Antreesy in #15583 (comment)