Crunchy Keyboard

[Arterion]

The bottom right buttons on my physical keyboard make a kind of crunching sound when I press them. Any idea what's going on? It wasn't that way at first, but one day it just started. At some point, it went away, and now it's back. I don't know how to explain it except that it has a little more resistance pressing the keys in and makes a little crunching or clicking sound.

It was all the way up into the M and K keys, but now it's just the down and right arrows and enter.