Well, that’s maybe a coincidence but I’ve just solved a similar Qt-* error in VLC (same Qt: Session management error: None of the authentication protocols specified are supported).
After searching a bit, I succeeded with these commands:
sudo rm /var/cache/fontconfig/*
rm ~/.cache/fontconfig/*
fc-cache -r
sudo fc-cache -r
These commands were present in my bash history and I can remember such a bug using snap (snap store ?).
I don’t know if it will solve your problem. Anyway this fonts-related trick has absolutely imho to banished from non-geek snap user experience. What I did these last days: refresh quadrapassel, remove brave, install code. Nothing more, so I did nothing weird.