All heals are based on the maximum HP of characters - the listed number for the heal (like 2000 in this case) is the heal's CAP. Usually, all heals easily hit the cap amount. But, for new players who don't yet have 6x LMB SSR Eidolons equipped, they might not have enough max HP to get the full heals.
So I assume you're fairly new to the game? As you get stronger, that heal will get stronger and stronger until it hits 2000.