Supabase has introduced four new features for its Auth system: Identity Linking, Session Control, Leaked Password Protection, and Auth Hooks with Postgres functions. Identity Linking allows developers to manually link two separate identities, while Session Control provides more control over user sessions. Leaked Password Protection prevents users from using leaked passwords by integrating the HaveIBeenPwned.org Pwned Passwords API. Lastly, Auth Hooks enable customization of standard Auth features through Postgres functions or webhooks.