Firebase – onAuthStateChanged does not return correct formatted object

My app is working correctly until a few minutes ago.

According to documentation, the user object returned will have following properties:

firebase.auth().onAuthStateChanged(function(user) {   if (user) {     var displayName = user.displayName;     var email = user.email;     var emailVerified = user.emailVerified;     var photoURL = user.photoURL;     var isAnonymous = user.isAnonymous;     var uid = user.uid;     var providerData = user.providerData;   } else {     // User is signed out.   } }); 

If I want to access uid, I can just call user.uid.

But the problem is I discovered this behavior is broken while I was developing new features a few minutes ago.

If I want to access properties like uid or email, now I need to access it like this:

user._user.uid or user._user.email

Why does this happened?

Is Firebase doing any update?