From first post in this thread:
On my media player, X crashes once in a while. I'm not sure why
A quick follow-up in case this information is helpful to someone: It turns out that all the crashes happen when watching a video in Brave (extension from repo) or Chrome (.deb -> homebrewed .tcz) in fullscreen mode. It doesn't happen every time, only once in a great while. Unfortunately, /var/log/Xorg.0.log shows nothing helpful, just a segfault. mpv in fullscreen mode, on the other hand, never causes a crash.
The media player is now running TCL14-alpha 64-bit rather than TCL13.1 64-bit. The TCL version makes no difference.
I don't think there is anything to be done about it. Just something to be aware of, I guess.