Lightening blast costs 3 mana?

Hello, since today I realised that my lightening blast was now costing 3 mana, but I can’t find where it comes from. I checked my talent skills, my passives, my stuff (i’m only level 48) but I can’t find anything increasing the mana cost of lightening blast, does anyone have an idea please ?
I’ve also checked last patch note but saw nothing

How much were you expecting it to cost?

Some weapons have a “-3” mana cost at the top.

I’d bet you used to have that equipped, so you thought the normal cost was 0, but in fact, it’s 3.

Maybe it’s that but last epoch tools says this spell has 0 mana cost (i could compare with an other mage to be sure)

edit : nevermind I created a new mage and this spell has a base mana cost of 3 haha ^^'.
Thank you !

Wands and Staves have -3 mana cost implicit on them. If you swapped to a Scepter, you might have noticed the mana cost return. There is an affix that fixes that problem giving -3 mana at T1-T5 and -4 at T6 and -5 at T7.