What's team-scoped user identifier?

I am integrating with Sign In with Apple, but I've got confused by the doc. It says here and here that the user identifier is team-scoped and is the same across all the apps in the development team associated with my Apple Developer account. Now my questions are as follow:

  1. What if I leave the team? Will my app still get the old user identifier? Likewise, what if I joined a team?
  2. Does it mean that apps developed by different developers get the same user identifier as long as these developers are in the same team?
  3. How does it work if I join multiple teams?