Create Teams OnlineMeeting via Graph API using delagated permission now get "No application access policy"

I was able to created (Teams) OnlineMeetings via graph API with my own app registration and delegated permissions using device_code flow and the /me endpoint. I left the code untouched but now, I do get a "No application access policy found for this app" [403].

As far as I know, when not using application permission - I don't need a further tenant admin setup. The code works in the same way when creating Calendar events, but fails now for OnlineMeetings.

Are there any significant changes for delegated permissions concerning the /v1.0/me/onlineMeetings endpoint? Or did my tenant admin modified something?