Malevolence + Divine Blessing bugged cost in 3.21?

Hi, im not 100% sure if it's a bug or not (im kind of beginner). In previous League Malevolence BASE mana cost was around 400 (Image)

Right now then i tried to make the same thing in 3.21 the base cost is a lot higher than before. Couldn't find any patch note about it.




**Imporant**
Of course there is 10% difference in reduce cost multiplier, but that's not the case. I tested that in game and cost in the end is still different.

A major factor to the cost is how big your mana pool is because Malevolence is a 50% aura (the blessing still uses this value to calculate cost). So if you have more mana now than you did in the previous league, that would explain the difference.