Loading a video in mpv media player sometimes freezes my desktop (Ubuntu 21.10)
Haven't thoroughly tested, but I'm pretty sure I've found the culprit. In the Ubuntu package, mpv.confis set so that hwdec=vaapi by default. The mpv manual says that this can cause issues and recommends outright deleting the config file, but I just changed it to hwdec=no which is the default.
I'll update this if I continue to face the same issues but for now I'm fairly confident this is the fix.