I was getting the error at the end of authentication (after 2FA) during log in that required username and password. I installed it from the FossDroid repos in my main profile, and cloned it to my secondary profile.
After enough trying things, it seems that if you still have an active login cookie in another user profile that's connecting via a different VPN server, you might get rejected by the official Bitwarden cloud server. Alternatively it might be related to specific VPN endpoints being blacklisted. I'm not sure, but resetting my VPN connection in the secondary user profile and trying again it started working again.