Removing the true damage from conq and increasing the healing actually overall nerfed the healing.

before conq used to take 8% of all ur damage and turn it into true damage and u would heal for that, so if your playing aatrox and you hit a 3rd q on 2 people and do like 1k damage with it stacked, you would, deal 80 true damage and heal 80 health.

now its just flat healing for 15% of damage dealt, no true damage. So when you do the same thing but this time there is no true damage and assuming everyone has 100 armor cus that's around the average amount of armor on each champion, which is 50% damage reduction which cuts it in half, so your healing for 15% of 500 which is 75 health.

So not only are you now healing for less, you are also doing less damage because now your not doing true damage, so they literally just nerfed conq and placebo effected everyone to believe it became overpowered after the changes so they have a reason to nerf it.