Explain this map mod "Monsters gain X% of maximum life as extra maximum energy shield"

If I am understanding this right, lets say if X is 50% and monster has 100 HP, that would mean now monster has 50 ES and 100 HP right?

What I am seeing consistently is that instead, taking the above example, they get WAY MORE ES than what the X% says. Almost like X% x2 amount.

if u have map modifier effects on atlas tree, all map mods scale with % from it, wtf u dont know it? And es faster recover than life

Of course I know. You answered nothing.