Regarding the total damage you would deal at 5 stacks. I remember before it would show you the total damage your ultimate would deal as if you had 5 stacks with your passive AD accounted into it(which adds in the bonus AD).
Right now it shows how much damage your ultimate would deal at 5 stacks without your bonus AD from your passive unless you currently have it active.
For the examples below I'm going to use having 20 bonus AD from runes and items and assume my passive gives 50 bonus AD.
How it looks like right now: Your ultimate deals 100+15 true damage, increasing by 20% for each stack of hemorrhage on the target(maximum damage 200+30).
How it's supposed to look like and used to look like: Your ultimate deals 100+15 true damage, increasing by 20% for each stack of hemorrhage on the target(maximum damage 200+105).
This wouldn't be a buff, this wouldn't separate the good Darius from the great, this is just going back to how it used to be. It's confusing at level 18 seeing my ultimate tooltip say it deals around 700 damage at 5 stacks.
This issue started a few months ago. I'm assuming it's a tooltip error.