I'm sorry, but if you're halfway adept in both writing and using modern LLMs, every single telltale sign exists in this material. OP is right to call it into question, and you are embodying the very caricature which you're attempting to assign to him in your fallacious assault on character and authority.

Let's return to a more positive discourse, and not immediately become vitriolic when someone rightfully points out that material marketing a book might not be genuinely produced by a human. We should expect more transparency from the author around the use of AI in their writing and marketing process if we are expected to give this book any attention.