Your aura of vitality is in those 83 hp.
3 percent is from bees or some similar improvement.
I checked it also on regular units it works fine. Simply check your units hp before ordering production, it should be 80 and fter its being produced it becomes 83 because of 3 essences vitality. Its not that good for single unit stacks like golems, but noticable for regular units when they become groups or bigger.