PublicKeyCredentialCreationOptions.pubKeyCredParamsIn the options for a Web Authentication credential registration request, the caller can specify a list of cryptographic algorithm identifiers in the pubKeyCredParams field.
If left unspecified, Chrome uses the default values of ES256 (-7) and RS256 (-257).
In some situations, a Relying Party developer might choose to augment this list with other identifiers. However, developers should be aware that excluding either of the default identifiers has compatibility risks. In particular, RS256 is necessary for compatibility with Microsoft Windows platform authenticators. ES256 is a widely supported algorithm and is compatible with most other platform authenticators and roaming authenticators.
Therefore a Relying Party that uses an algorithm identifier list that omits either of those values will see registration failures when users attempt to use incompatible authenticators.