Time Machine has selective backups
Why would my Time Machine backups show empty folders for the second user of the Mac Mini? Shouln't EVERYTHING be backed up?
Question marked as
It appears to me that you are looking at the Time Machine backups by means of a Finder window.
I assume you are referring to the /Users/susank.../Documents folder.
Because you are using Finder, and you are not signed into the susank... user account, you don't have the proper privileges to view the contents of that user's folders. The red 'prohibited' icon on the folder is an indicator of that.
The problem is not that the folder is empty, it's that Finder won't show you what is in it. Finder is working as designed.
If you want to see the contents of those folders, sign into that Mac user account and take another look at the backup. Best to use the "Browser backups" feature of Time Machine rather than the Finder window.
Recover files using Time Machine and Spotlight on Mac - Apple Support
EDIT -
In fact, even if you browse the TM backups with the Time Machine interface, those folders that belong to a different user than that which is signed in will display the prohibited icon and their contents cannot be viewed.