Hi there, My personal Apple ID happens to be quite old, actually from the mac.com era. My Apple ID is still a @mac.com email address, but my main/ default email address is a @gmail.com address. For any other occasions, emails I receive from Apple are properly routed to my @gmail.com email. But if I sign up to an app using Sign in with Apple and not disclosing my actual email address to the app, Apple will by default relay email sent by the app developer to my @mac.com email. I can change this behavior by going into my Apple ID settings and change my default transfer email address. But it does not seem right that Sign in with Apple picked as default a field that may actually not be an email address. It should have picked the default email for my Apple ID.