...
When
User Verificationis set toNo Required, this doesn’t mean that User Verification is never performed. For instance, when registering a FIDO2 security key that has PIN set, user verification might be required depending on the application.When
User VerificationisPreferred, the user experience depends on whether or not a PIN is set or a fingerprint is enrolled on the user’s security key. To achieve a uniform user experience, explicitly setuserVerificationUser Verificationto either Not Required orRequiredaccording to your specific use case.When
User Verificationisrequired, keep in mind that registration or authentication will fail in the following cases:the user has not set a PIN or enrolled a fingerprint on his or her security key. Some browsers will ask the user to set a PIN or enroll a fingerprint during registration, but others don’t. So, the behaviour cannot in general be relied on.
the user is using a security key that does not support user verification (for instance, a U2F key)
the user is using a browser that does not support user verification (for instance, browsers that implement CTAP1 only)
...