Backup limitations for Teams site collections
Following are the limitations of the Teams site collection connector:
The files that are posted in Teams are stored in the user's OneDrive.
The file that is shared in a Teams channel is stored in a private channel or on the SharePoint site for the team.
If you back up OneDrive or SharePoint sites using SharePoint connectors and stubbing is enabled, the files are replaced by stubbed URLs in SharePoint sites. The references in these posts still point to the earlier URLs that are no longer available. To access such files, you can open the tab in the chat or channel.