AADSTS1001010: The client or resource application is missing service principal in the tenant

Hi,

I configured an Azure Bot, and added Azure Communication Service - Chat as a Channel. Everything worked fine.

Today, I try to access this ACS channel to get the automatically generated ACS Id, and I get a (weird) error page

When analyzing the error message, it seems like the error is:

AADSTS1001010: The client or resource application: 779fbbea-18c9-4e4c-8790-aa1e55c2cacb is missing service principal in the tenant: 33e01921-4d64-4f8c-a055-5bdaffd5e33d. See instructions here: https://go.microsoft.com/fwlink/?linkid=2167121.

I am connected as an admin and owner of the account. Tried to understand what is happening with azure cli, and the azure API, but I get the exact same error...

Any idea of this weird issue ? It was working perfectly well before...