RAONICALIASlittlekoalaHaving the same issue here, also tried everything that you mentioned, rolling back nvidia drivers didn't help, i think it may have something to do with some related packages.thanks for the heads up! I think the issue might be something related to TF2's low-level graphics, in that case, because of how OP's game instantly crashed after trying to change sens. Might be a good idea to try using different SDL2 versions
Thanks for the recommendation ;), however the issue has been temporarily fixed, here is the link for OP:
can confirm that downgrading lib32-libx11 package to 1.8.2-2 stopped crashes.