A new login technique is becoming available in 2023: the passkey. The passkey promises to solve phishing and prevent password reuse. But lots of smart and security-oriented folks are confused about what exactly a passkey is. There’s a good reason for that. A passkey is in some sense one of two (or three) different things, depending on how it’s stored.
As far as I know the Bitwarden browser plugin for Firefox does not yet support WebAuthn/Passkeys, as it’s still on the September release. Chrome is already on the October version. A build of Vaultwarden from yesterday onwards should support storing it, once your browser is ready.