Unbinding the Party Voice Chat key (Default Y) fixes this. I've no idea why
Credit to https://forums.playdeadlock.com/threads/linux-steam-game-crashes-when-using-text-chat-while-in-a-party.121535/post-230104
I've noticed these crashes on Arch as well, and they seem to happen when using voice coms or typing, either in chat box, searches, or the report function. I'm not sure what is causing it but there are plenty of reports of Linux users experiencing the same issue. I'd just avoid using...
I'm also seeing this issue and it looks like a lot of others on the forums are as well, all on Linux, mostly using Arch derived systems
https://forums.playdeadlock.com/threads/typing-in-chat-crashes-both-game-and-steam-linux.45897/...