Tested against bitwarden unified docker image: no error.
If I quit firefox while the add-on is logged in, the next time firefox starts and I login (2fa webauthn yubikey) it says: “Can’t recover login challenge” but I’m actually logged in and can use my vault.
Firefox addon setting: Logout on browser restart.
If I logout and login immediately: no error
If I logout, restart firefox, login: no error
Error is only following browser restart while logged in.
Not happening with web vault, only firefox addon.