This is likely due to their permissions, as they are part of a group that has permissions to these other reports, such as SYSTEM.
In FinOps
Navigate to System
Then go to Report Structure, Document Layouts
Click Edit Structure
Expand the reports section and filter based on the other group this user is a part of.
Untick the permissions to these reports.
You may need to add these permissions by a group basis or user to allow the rest of the users the same permissions as before.