Andrzej Sapkowski recently wrote a prequel to his Witcher novels, Crossroads of Ravens. At an event to publicize that novel, our colleagues at GamesRadar asked the author if he'd been involved in any part of the development of The Witcher 4. And he said, basically: nope.
While explaining that the developers at CD Projekt Red did ask for advice and extra details about the setting while working on the previous games, these days apparently "it's so rare" that CDPR contact him to ask about the lore. Which makes sense, given how much the studio has added to it over the course of the Witcher games, like building Witcher schools based on an off-hand reference he threw in before regretting it.
