The login security feature provided by Cloudflare is called Cloudflare Access. It is part of Cloudflare’s Zero Trust security platform, which helps secure, authenticate, and monitor user access to applications. Cloudflare Access acts as a secure gateway, ensuring that only authorized users can access specific resources, often integrating with identity providers for authentication and offering features like multi-factor authentication (MFA) and single sign-on (SSO).

get to it from dash.cloudfare.com > navigate to access >

and you will see that you have a cloudfar access application