Somewhat related, i recently ran into the issue, after i created an account on Confer.to [1] on my Desktop, i couldn't login on my iPad / iOS with Proton Pass and/or Bitwarden.

The error message was: "Error: "Authenticator did not return a PRF result — this passkey probably isn’t PRF-capable."

So i now have an account, but can only use it on my Desktop. (can't change to a password login either, it's Passkeys only...)

[1] end-to-end encrypted AI, developed by Moxie Marlinspike, the founder of Signal: https://confer.to/