Comment 19 for bug 1908429

With gnome-shell 3.36.9-0ubuntu0.20.04.2 I too see this with only the built-in "Desktop Icons", "Ubuntu AppIndicators", "Ubuntu Dock" extensions and no further extensions in ~/.local/share/gnome-shell/

$ journalctl -S -1hour | grep 'Jan 07 08:19:35' | sort | uniq -c
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     22 Jan 07 08:19:35 LAP125300 gnome-shell[3286]: Attempting to call back into JSAPI during the sweeping phase of GC. This is most likely caused by not destroying a Clutter actor or Gtk+ widget with ::destroy signals connected, but can also be caused by using the destroy(), dispose(), or remove() vfuncs. Because it would crash the application, it has been blocked and the JS callback not invoked.
   4314 Jan 07 08:19:35 LAP125300 gnome-shell[3286]: Attempting to run a JS callback during garbage collection. This is most likely caused by destroying a Clutter actor or GTK widget with ::destroy signal connected, or using the destroy(), dispose(), or remove() vfuncs. Because it would crash the application, it has been blocked.
     22 Jan 07 08:19:35 LAP125300 gnome-shell[3286]: The offending callback was paint(), a vfunc.
   4291 Jan 07 08:19:35 LAP125300 gnome-shell[3286]: The offending callback was SourceFunc().
     22 Jan 07 08:19:35 LAP125300 gnome-shell[3286]: The offending signal was paint on Gjs_ubuntu-dock_ubuntu_com_docking_DashToDock 0x5581d33fc7d0.