Another player and myself experienced this problem lately -- when typing T to chat, the letter "t" will appear in the chat and we'll have to delete that "t". I can't reliably reproduce it but I thought maybe somebody knows why.
I have that issue with the console, having to delete the § character out of the way most of the time.
I have this issue every time. T for normal chat, Y for team chat, I have to delete the letter each time I want to chat.
Are all of you on 0.8.2 linux SDL? I heard the chat T issue was fixed in autobuilds (though SDL autobuild might have bugged fullscreen currently).
The console was also bugged at some point but not anymore so maybe also try git/autobuild?
To get an autobuild, make a backup of your Xonotic folder (the unpacked zip), then run one of the scripts in misc/tools/rsync-updater.
@martin-t, you are right. I play both the latest git and 0.8.2 (both SDL and GLX) so the problem was never consistent enough for me to tell what's going on. Now that you said it, yes, it was 0.8.2 SDL that has the problem.