Troubleshooting Grafana Cloud OAuth (EntraID/Azure AD)

Hey Guys,
I am Trying to set up Grafana OAuth (Microsoft Entra ID) in my Grafana Cloud Instance. In EntraID Logs the Logins are successful, but grafana throws an error on the login Page…
One user worked, don’t now how, but the rest didn’t. Now this is likely a misconfiguration on my side, but my problem is, how can i debug this on grafana cloud. In a self hosted instance i would just check the logs and see what i did wrong.
Does anybody have an Idea on how to troubleshoot this in Grafana Cloud?

Thanks for all hints:)

What is that error message, pls?