The problem affects desktop machines not yet running Debian bullseye. The problem will resolve itself upon the next update, at the latest tomorrow (May 29th) at 1 p.m. Please contact us if you need access back sooner.

Post Mortem: An error in our config management, that unfortunately wasn't caught in our tests during CI, made machines fall back to our old authentication system without updating the PAM configuration. Since group membership could not be resolved by PAM, login was impossible.

We have added new tests to our CI to not repeat this mistake and have made our PAM config more robust.