I recently installed linux on a MSI laptop that has a webcam function key switch. For some reason (could have been me), it was off and I just assumed that the camera wasn't working with linux, or that there was a hardware issue. I almost sent it back.
I never owned a laptop with that kind of switch before, so I wasn't looking for this, and the keyboard icon [1] looked like some kind of screen contrast button to me...
Oh man, this happened to me many years ago as well with wifi. The keyboard had a wifi toggle (which in linux translated into rfkill) as a mod to an Fn key. Took me hours to realize that was a thing. I was literally debugging the kernel trying to figure out why the driver was spitting out "rfkill enabled" when "it shouldn't" only to realize a simple hold of Fn + F9 (or whatever it was) fixed the problem right up :facepalm:
[1] https://imgur.com/a/2Oe2k4e