Is there a way for me to determine whether the user has been removed from Firebase authentication?

edit

Yes, you can use the Firebase authentication API to check whether a user has been removed from Firebase authentication.

You can use the onAuthStateChanged() method to listen for changes in the user's authentication state. If the user has been removed or deleted from Firebase authentication, the user object returned by this method will be null. Here's an example:

firebase.auth().onAuthStateChanged(function(user) {
  if (user) {
    // User is signed in.
  } else {
    // User is signed out or has been removed/deleted.
  }
});

In the above example, if the user object returned is null, it means the user has been signed out or removed from Firebase authentication.