Do you still have the issue if you update the latest version? If so, can you share the output of swupd info and swupd bundle-list?
The only thing I can think of is that PyGObject, where this module comes from, was update to Python 3.8 compatibility but that was a week ago. I’m not seeing this on 31960.
I had the same problem starting up gnome-tweaks.
Then I realized that I also had anaconda3 installed which
comes with its own python runtime and that didn’t
have pygobject installed. I removed anaconda3 and
gnome-tweaks started working.