Mana cost efficiency bugged ?

Hello, I have noticed that when I equip an amulet with the Conservative Casting anoint, the mana cost for Ice Nova is increased instead of being reduced. Based on the description of the Mana Cost Efficiency effect, I understand that it should lower the mana cost of spells. However, the game displays an increase.

I have attached a screenshot for reference.

"

Unusual_Research#7606 wrote:

However, the game displays an increase.

+2 levels on amulet, increases mana cost.

"

Unusual_Research#7606 wrote:

However, the game displays an increase.

The amulet also has +2 levels to all spell skills.
Increasing the skill's level increases the Mana Cost.