/usr/bin/gnome-shell:gnome-shell: ../../src/xcb_io.c:260: poll_for_event: P\305\231edpoklad \342\200\236!xcb_xlib_threads_sequence_lost\342\200\234 nespln\304\233n.

[errors.ubuntu.com bug bridge]

The Ubuntu Error Tracker has been receiving reports about a problem regarding gnome-shell. This problem was most recently seen with package version 3.36.3-1ubuntu1~20.04.2, the problem page at https://errors.ubuntu.com/problem/14911e4a22eec995bc364278c0490d8bfea557dd contains more details, including versions of packages affected, stacktrace or traceback, and individual crash reports.
If you do not have access to the Ubuntu Error Tracker and are a software developer, you can request it at http://forms.canonical.com/reports/.

[Marco Trevisan (Treviño) (3v1n0)]

Seems similar to https://bugs.launchpad.net/mutter/+bug/1877075 that was supposed to be fixed, but not in all the cases, it seems.