I don’t find this at all. Not that many fiction books use a lot of AI prose it seems. Maybe nonfiction is worse?
I'm certainly observing AI smells from a high proportion of the books I read from O'Reilly and Packt since 2023. Authors don't attempt to hide it and some publish the work as if we didn't have a back catalog to distinguish the genuine article from a lazy prompt-driven manuscript.
I'm not seeing the same from the translated fiction works I've picked up in the same time period, thankfully.
What facts are you hanging that hat on?