A final farewell to ClientLogin, OAuth 1.0 (3LO), AuthSub, and OpenID 2.0 - Google Developers Blog

What this post added

This post announces the deprecation and eventual shutdown of ClientLogin, OAuth 1.0 (3LO), AuthSub, and OpenID 2.0. It highlights the transition to OAuth 2.0 as the preferred and more secure authentication protocol for Google APIs, encouraging developers to migrate their applications to avoid service disruptions.