I’m currently using a snap application (XMind) for my school projects. It looks fine at first, but, when prompted to the file manager, all characters are just… squares. Everything, from the text inside buttons, to file names… everything.
Have you tried resetting your font cache? You can delete the .cache/fontconfig folder in your home directory to do so, it often helps with font problems in snap applications.
Nevermind, I just tested myself and can reproduce the issue, its not related to a broken font cache.
The snap maintainer needs to fix this, for now I’d recommend you to use the AUR version instead.