It's factually incorrect to imply that fhirUser is a required scope to get an id_token claim. Should either mention the fhirUser claim or remove reference to the fhirUser scope.

Existing Wording:

Per SMART, when scopes of openid and fhirUser are granted, the authorization server additionally sends the current user's identity in an id_token\.

Proposed Wording:

Per SMART, when scopes of openid and fhirUser are granted, the authorization server additionally sends the current user's identity in an id_token and fhirUser claim, respectively\.