I've been playing on the Linux version of the game for years and there's always been a bug where, when typing certain characters with Shift+ in the chat sometimes makes that character autorepeat, until I type the same character again; this happens seemingly at random, and only with certain characters, like '/', '^', and ';'. Of course I'm most annoyed by the '/' autorepeat. I should mention that I'm using an Italian keyboard layout.
I've never reported this issue before because it doesn't seem anyone else has ever had it. I've actually had a look at the nenya code to see if I could debug this myself, but it was too complicated to extract the portion that would help me reproduce the issue (and I don't think building the whole game would be feasible). It'd be nice if I could get any help, or even just feedback from other players who may or may not have the same issue
I have nothing useful to say at this moment, but I feel you. I'm experiencing the same issue. The only way to prevent it going entirely nuts seems to be just Alt-Tabbing out of the game and back in.