I sometimes experience this when closing a tab on gnome-console (kgx). I also
got this when trying to shift+del a selection of files on nautilus. In both
cases the whole app will crash and close.
It is really random, but since I work in my terminal a lot I usually get 1 or 2
crashes per day.

Just had a situation here in gnome-console and got this:
2023-04-11T13:44:37.203800-03:00 behemoth org.gnome.Console[3584]:
Gdk:ERROR:../../../gdk/x11/gdksurface-x11.c:606:sync_counter_for_end_frame:
assertion failed: (impl->toplevel->extended_update_counter != None)
2023-04-11T13:44:37.203843-03:00 behemoth org.gnome.Console[3584]: Bail out!
Gdk:ERROR:../../../gdk/x11/gdksurface-x11.c:606:sync_counter_for_end_frame:
assertion failed: (impl->toplevel->extended_update_counter != None)

This is the related upstream issue:
https://gitlab.gnome.org/GNOME/gtk/-/issues/5440

Control: retitle -1 libgtk-4-1: intermittent crashes on X11 in sync_counter_for_end_frame: assertion failed: (impl->toplevel->extended_update_counter != None)
Control: forwarded -1 https://gitlab.gnome.org/GNOME/gtk/-/issues/5440

For future reference, this is the least interesting/distinctive part of the
assertion failure message, and the least useful to distinguish between
different crashes. The parts that matter most are the function that has the
assertion (in this case sync_counter_for_end_frame) and the assertion itself
(in this case impl->toplevel->extended_update_counter != None).

    smcv