Heyu,
So since I really needed the app, T tried some things and it works now.
This is what I did to fix it:
- I first uninstalled teams by opening the .deb file (I did it with Ubuntu Software).
- After that I deleted the whole teams-folder with all the informations. This was the path: ~/.config/Microsoft/Microsoft Teams/
- If you deleted the folder "Microsoft Teams" install the app again with the .deb file
- At this point I could log into my new school-organization.
I hope it was helpful.
Tag me if you have another result.
Kind regards
Hava