iamdodgy.com
This site will attempt to inject a cookie into the widest scope possible, before attacking the victim site. The attack will only work if there is no PHPSESSID cookie set for naiveandtrusting.com, so do not visit that site until after you have injected the cookie. Alternatively, remove its cookie before retrying.
The sign in option in the top right does not impact the application, however its presence allows you to trigger conditional access rules for your Entra tenant.