She had slits in her eyes in the first reveal trailer too so it's nothing new. Seems she did undergo mutations if she has Witcher eyes.

Ahh Google it

Despite original lor and the fact she was never supposed to become a witcher, the devil made her one anyways to avoid making new protagonist. And the author of the books apparently approved this, so like it or not, it's now Canon. She's the first female witcher.

First and only since I think the Elder blood is what made it possible somehow.

My biggest concern is wether or not the new VA will be any good since Jo sat a high bar