If I understand it correctly (I had some trouble wrapping my head around the exact attack vector): The problem here is that browsers allow redirecting users to

If I understand it correctly (I had some trouble wrapping my head around the exact attack vector): The problem here is that browsers allow redirecting users to the installed passkey implementation/"backend" in the same way that camera and dedicated QR scanner apps legitimately use to initiate cross-device authentication via (what used to be called) caBLE, right? In other words, the attacker primes the user for an upcoming authentication on-device authentication, but in reality initiates an off-device authentication to their own device. And the fix is presumably to not accept off-device authentication intents over anything that's not a QR scan, or at least filter them out in the browser?