Didn't Outlook.com famously rolled out passkeys with no recovery option and no option to sign in using username and password once enrolled. So if you lost your trusted device, you couldn't sign in, nor could Microsoft send you an email, because... Outlook.com is your email provider.

I don't know if they fixed it, they probably did. Edit: Maybe not, because the recovery option at the end is just nuts: https://learn.microsoft.com/en-us/answers/questions/5454924/...