As per documentation it is confirmed that system tables include data from all workspaces in your account, but they can only be accessed by a workspace with Unity Catalog, you can restrict which admins has access to this system tables.

It is not possible to limit system tables to show information only for the specific workspace where the query is being run. System tables are designed to contain operational data for all workspaces in your account deployed within the same cloud region. They are an account-level regionalized concept that is cross-workspace, meaning they include data from all workspaces within the same region and cannot be restricted to a single workspace.