tex-file not recognised (on Fedora Silverblue / Bluefin)

[Taxicletter]

Hi,
I switched from Fedora KDE to Bluefin. Tex as a filetype is not recognised anymore.
The system doesn't show Zettlr as application to open tex-files with. Even a tex-file made with Zettlr, is not visible if you choose open from Zettlr's menu and it's not in the recent files menu.
I'm using the Flatpak version, maybe I could try the AppImage.

I only need Zettlr to recognise the file type, because I have my own export profile. There you have to point to the tex file, but it's not recognised there either.

EDIT: With the app-image, you can open a tex-file with Zettlr, it shows in the menu. It also shows when you choose "open", but there it's greyed out. Exporting doesn't work (but I moved configuration files between the Flatpak and AppImage version and broke something doing so)