I was typing on my Keychron K2 keyboard today and realised that I hadn't used the function keys at all. Not that I hadn't tried a few times, it's just that the function keys were linked to the media keys for the laptop I was using. When I pressed the F2 key it would increase the screen brightness, which was fine, but I realised that I had missed using the function keys for a while.
I was using Ubuntu 20.04 and there appeared to be no option to turn this off in the settings. After a little research I found a solution to the problem.