Reading the docs, i realize that in Flutter Web the signIn method should not be used and will be deprecated, it is better to use a mix of signInSilently method, but it sometimes fails if user closes it once and it doesn't open anymore (for security i guess).

Another way they recommend it's to use their renderButton, it works, but it's not customizable.

In my case, I'm using Firebase, so i did it this way

FirebaseAuth.instance.signInWithPopup(GoogleAuthProvider());

Of course i need to have previous firebase config.

However, i think that they should improve a real alternative for signIn()