The Backup of SharePoint sites displays the following error:
Failed to initialize site processing: /contentstorage/CSP_<guid>, error: The remote server returned an error: (401) Unauthorized.
Microsoft recently launched a new feature called "Microsoft Loop." This application creates a SharePoint site to store shared content that can be accessed by users who have been invited to use Loop. The URL of these sites contains the "contentstorage" identifier.
For more information about Loop, you can visit these resources:
These sites have unique permissions assigned to them, and currently, Veeam Backup for Microsoft 365 does not support them. However, once Microsoft Loop becomes generally available, support for this feature will be developed.