I have just discovered on Twitter that there’s currently a problem with Teams Backup in Veeam Backup for Office 365 which could affect many installations.
It looks like Microsoft did change something on their side and so Teams backup is failing with the following error: “Object reference not set to an instance of an object”
If you are affected by this problem, you can request the hotfix from Veeam Support.
Here is the corresponding R&D forums topic: https://forums.veeam.com/veeam-backup-for-office-365-f47/teams-backup-failing-with-object-reference-not-set-to-an-instance-of-an-object-t76162.html