@Engineer This is supposed to be added by the browser itself: https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/Referer. Is there any policy that can be enabled for this in WKWebView since Safari has this or we should only use SFSafariViewController if that behavior is needed?

Seems the domain https://register.appattest.apple.com cannot be resolved at all. The development domain is still reachable.