Whether on brave, firefox or librewolf, a recent update of the Bitwarden extension does not connect to the vaultwarden server , whether locally or remotely. According to Grok, this is the root cause:
The Bitwarden extension (newer version) is trying to call a new API endpoint:https://ciuziiad.local/identity/accounts/prelogin/passwordBut
your Vaultwarden server returns 404 Not Found because it doesn’t have that endpoint yet.
Solution would be to update Vaultwarden server .This endpoint was added very recently (in Vaultwarden 1.35.x series). Your server is older than the current Bitwarden extension.
Therefore, until StartOS updates Vaultwarden, I have reverted to older versions of the Bitwarden extension (like 2025.12.0) on all my browsers and it works … until some update sneaks in despite my disabling it, and I have to do it again.