The type of credProps.authenticatorDisplayName has changed in the WebAuthn spec: https://github.com/w3c/webauthn/pull/2115 This issue may be irrelevant if credProps.authenticatorDisplayName is not yet implemented.
<rdar://problem/135266998>
I tried to search for `authenticatorDisplayName` on GitHub WebKit repo but couldn't find anything so I think it is yet to be implemented.