Our sign in flow works flawlessly on every browser except Safari on iOS13 and latest Safari on Catalina. It *only* breaks when the native Safari auth popup are involved.
We follow the flow described in: https://developer.apple.com/documentation/signinwithapplejs/incorporating_sign_in_with_apple_into_other_platforms
Once you click on the sign in button on our web app no network requests are shown in Safari dev console, even if you cancel or attempt to sign in which makes it hard to debug what the issue is.
Is there any more info I can provide ? (I'll configure wireshark or similar tomorrow and see requests if any are being made).
When you click cancel the popup closes and returns to our web app (albeit in a broken state since never received a response). When you click sign in it fails and native pop-up remains open.
