What would happen to a pulley system if the load were increased?

Ideal mechanical advantage is the mechanical advantage when there is no friction.

It is the mechanical advantage when the efficiency of the pullefy system is 100%. It is a constant for that system of pulleys. Therfore it is not affected by increasing or decreasing the load.

But actual mechanical advantage will be less than this ideal mechanical advantage due to friction. In other Words the efficiency will be less than 100 %. If the efficiency is 80%, it implies 20% is wasted due to friction while lifting a load.

If we increase the load the friction also increases and hence the efficiency will decrease with the load.