I’m not aware of this. Maybe you can provide it.

It is considered as a hobby in Germany. In terms of tax and funding law, working on open source projects does not count as volunteering, unlike working in a sports club, etc.

Okay but this also implies that Vaultwarden with your passwords was compromised. I understand your point having passwords and 2FA in two separate places but in the end having 2FA at all is better than not having it even if you have it in the same place.

You could also use Vaultwarden an open source fork of Bitwarden. It works with the official app and don’t know why you need Ente for 2FA as Bitwarden/Vaultwarden also covers that AFAIK