There are Azure apps but is there still an account configured on the agent?

There have been some recent changes due to MSFT changes

https://kb.commvault.com/article/84695

Bottom contains steps for each app. Also note you may have to reauthorize the apps

The customer had done something on their end, but still it bugs me. 
We always provide the Custom Configuration toolkit, the Office 365 helper wizard to our customers, so we never have a customer admin account stored in Commvault MS365 backups in that way. So unless I have overlooked something in the article, it is not applicable here.

What I do know, is that whenever we set up apps for Teams, we need the customer to type in the login for a Teams service account. This account will then be placed with permissions in all customer’s Teams channels.

Could it be that it was this account suddenly got MFA?