[eloeffler]

You can open your Firefox about:config and set security.webauthn.ctap2 to false.

This will cause a fallback to FIDO/U2F where possible and your browser will appear to not support FIDO2. I've observed this with the default Keycloak flow for Security Tokens. May be a bug, too...

I don't know if this works with Google but if you try it, let me know :)

This needs no restart of Firefox, so you can use it to quickly disable it instead of fully disabling it on your Hardwaretoken.