The formula isnt calculating modified HP properly. You add all your boosts up, eg. 30%+50%+20%=100% boost. Now when you take your base HP and multiply it by the boosts, it converts % to a decimal. So 100% would be 1.00. But before you take base HP×1.00, you add 1 to the decimal. In this example, that would be 2.00, because a 100% boost is double your base HP.
It looks like the formula is not adding the 1, so damage is much lower than it should be unless you have stupidly powerful gear.
Example: let’s say 10M base HP, 40% from gear, 10% from research, and 30% consumable. 10×(1+.40+.10+.30)=10×1.80=18
Then for the damage I’m assuming everyone has expert mythic glyph
If that 1 in the first step isnt added though, modified HP looks like 10×.80= 8, which screws it all up. It would explain why the damage is so much lower than it should be.