I just recently learned this when I tried to take a Teams call (ugh) with my Bluetooth earbuds, only to find that the microphone worked, but I couldn’t hear anything.
Turned out, by default, it had set the input as headset mode, but the output as stereo headphone mode, so I couldn’t hear anything.
Because that makes sense.
That’s still insane though… I will sometimes hit caps lock once or twice on a password screen to make sure it’s not on.