Same BadWolf that just now commented on your Nexus mod page. I have to go to sleep for work, have next few days off, but when I get home I will do that search on the model they used for the in game beginning movie and promotional photos like above. I still think that the deal to use the model's likeness fully, fell through and they had to recreate Yen's face. I think that was part of the game's release delay.
Edit/Update:
Okay, I couldn't lay it to rest yet...found this on Reddit:
From an article: "The biggest problem on the characters was Yennefer,” lead character artist Pawel Mielniczuk says. “ She changed a lot. We prepared like four versions of her face and she looks completely different. The first of them were released with the cosplayers guide…"It was heavily disliked by our community. That was a big disappointment for us. The picture was very unfortunate. That was the first time we showed the character and it’s very important for everybody, for the players and us, and it was just unfortunate. It was supposed to be a small cosplayers guide sent to a few people: unfortunately when you throw it to the internet it appears everywhere and there was a huge wave of criticism about the face. And the face was a scan. It took us almost half a year to find the proper face model for us. It was Klaudia Wróbel, a Polish model, and she was initially scanned for the Platige [Image - CGI company] movie - the movie that’s opening the game. There you can see her face; she’s scanned in there, modelled, put in the game and she’s playing Yennefer.
"We took the scanned face from the Platige Image and modelled it to work in game and… then the problems start. It didn’t match that good. We loved how Klaudia looked in pictures … but we didn’t manage to achieve the same look with our in-game model.” In the end, Yennefer was stylised - tweaked by hand for the game."
Link below
https://redd.it/46iolb
So, I was partly wrong on why they changed.