We are in the process of transferring our existing Apple account to a new account. We read the documentation and we realized that "Sign in with Apple" users needs to be migrated via API. This API seems to require "sub" which we are not currently storing in our systems. So we are planning to "collect subs" over a period before we can start transfer.
I want to make sure we are collecting correct data so I am looking for confirmation from Apple engineers on this. Should we get "sub" from "user" property in ASAuthorizationAppleIDCredential or by decoding identityToken and get "sub" from the token? I think both are same but wanted to double check. Thank you!