Hey folks, just wanted to say that I did have the exact same issue. With the same cloud version of n8n. I just updated the instance to 1.100.1 and removed all existing credenitals, deleted Entra App Registration and Enterprise App (which had all necessary scopes by the way) and now I am not even able to setup a new connection like described here (Microsoft credentials | n8n Docs). Now I am getting this one:
I was just about to start transferring my automations from Microsoft Power Automate to n8n and it hit me hard in the very beginning. Hope it is just me stupid and the community is able to help. Much appreciated!