Supporting Google Account username change in your app- Google Developers Blog

What this post added

This post details the implications of Google Account username changes for platforms integrating with 'Sign in with Google'. It explains how username changes affect user identification, particularly for platforms that rely on email addresses from ID tokens. It recommends using the stable 'subject ID' as the primary user identifier, providing email-based account recovery, and enabling email updates for traditional accounts to prevent duplicate accounts and ensure a smooth user experience.