It's in the rules. Emphasis mine:

Fake or False Consumer Reviews, Consumer Testimonials, and Celebrity Testimonials: The final rule addresses reviews and testimonials that misrepresent that they are by someone who does not exist, such as AI-generated fake reviews, or who did not have actual experience with the business or its products or services

If you covertly switch the product, then the reviews shown are from people who did not have actual experience with the product.