You had your Clarity SaaS environment set up to use SSO and able to log in using SSO. The application is landing on the classic UI, and should go to the Modern UX. Do you need to do anything to switch it to the Modern UX?
Release : 16.0.2
Component : Clarity SaaS Operations SSO
Chrome Developer tools trace shows the application is going to correct landing, Modern UX or /pm but for some reason SSO works and the Classic UI is coming up.
Make sure the New User Experience is activated in Clarity > Administration > System options.