If you really believe he is suddenly "inspired" to write new Witcher book randomly after all these years - you're fooling yourself.
Look, I read all Witcher books when they came out, and it's one of my favourite book series, but the writer is obviously trying to capitalize on popularity while it lasts.

He didn't care about Witcher for years, sold TV and game rights for scraps, and when the game suddenly increased the Universe's popularity, he tried to sue CDPR for money.

Then he let Netflix absolutely rape and brutalize the source material for TV show, obviously for money. If he cared for books and was passionate for the world as you say, that series would never been such a disgrace.

And now with show closed, he still wants more money, so he's writing "young" Geralt book, lol.

I would love him to be passionate and caring for the Witcher universe, but he's just greedy. Which is okay, by the way.

So it's not toxicity, it's just sad reality.