If you run Calibre in GNOME on current Rawhide, the entire session crashes. It seems like first Calibre crashes and somehow that takes down the GNOME session, though I'm not entirely sure as the available info isn't great. Reproduction is easy, though: install a current Rawhide Workstation live, install calibre, run it, complete the first-time run wizard, watch it explode. That's all you have to do. abrt generates a backtrace it refuses to report due to low quality, but I'll attach it.
Created attachment 1737432 [details] calibre backtrace from abrt
Created attachment 1737433 [details] journal messages up till end of crashed session here's the whole journal up until what looks to be the end of messages from the crashed session (after this I logged in again to report the issue).
the journal shows a gnome-shell stack trace, not sure why abrt/ccpp didn't catch it. systemd coredumpd did, though, I'll try and backtrace through that.
Filed https://gitlab.gnome.org/GNOME/mutter/-/issues/1567 for the Shell crash.
This bug appears to have been reported against 'rawhide' during the Fedora 34 development cycle. Changing version to 34.
This is closed upstream (worked around in mutter).