If you added a passkey from the Security page, it did not do anything, and the page told you it did. “Add a passkey” was the first thing that page recommended, and the card underneath said you could sign in with your fingerprint, face or password manager. A passkey added there was stored by SIMCOAI, and since sign-in moved to our secure sign-in service on 10 August nothing has read it — so it was never offered to you when you signed in.
Nothing was exposed and no account was less protected than before — a passkey is something you add, not something that replaces a check. What was wrong is that it left you believing you had a protection you did not have, which on a security page is the thing we least want to get wrong.
We have removed it rather than leave a button that cannot work. The card now says plainly that we cannot yet add a passkey to an account that already exists, and points you at This device under two-step verification — that uses exactly the same fingerprint or face, works today, and is asked for after your password. If you already had a passkey listed it is still shown and you can remove it; there was one, added in July.
The page’s recommendation is now two-step verification, which we have tested end to end. Adding a passkey to an existing account is something we still intend to offer, and we will say so here when it works.