Hi @HUIL
You may refer to the following article that explains the Level Aware Calculations in detail.
Coming to your question the RLS restricts access to data and that will happen before any other computations since the objective of security is to only give access to what the user should see. The Total from that persective of the Total for data the user has access to.
So, for example if I have access to Country India my total will be only for India though my dataset has data for Regions Europe, Asia and Africa. The person who should have a global view and has access to all data will see the overall total.
The PRE_FILTER and PRE_AGG have no role to play in the row level restrictions.