I have built a paginated report using a Data Set available on Power BI service in a Premium Workspace. The Data Set is using Row level security to limit what the users can and cannot see in the reports which is working according to plan. However, when we did some testing on the Paginated Reports the RLS was not honred neither when accessing the report nor when sending the paginated report as a subscription to users that should only see a specific amount of data.
As the following document mentions, paginated report RLS feature not similar to common power bi reports. It still required you to pass the username parameter to achieve RLS filter that enabled on reports side: