About Authenticating users with Sign in with Apple

If you use an Apple ID provider on a third-party system I believe that a token will be returned from the AppleID server after user authentication. I believe that a value of the key name "sub" as described in the following site will be returned at that time, but is this value constant for the same user?

https://developer.apple.com/documentation/sign_in_with_apple/sign_in_with_apple_rest_api/authenticating_users_with_sign_in_with_apple#:~:text=sub,for%20the%20user.