Not the OP, but this reminds me of a similar experience I had with a book called Space Opera a few months ago. Don't remember where I first heard of it, but it was being touted as comparable to the Hitchhiker's Guide. All the reviews on Amazon were 5 stars, and since the kindle version was only $5, I bought it without checking further. It turned out to be a pretty disappointing read, and nowhere near the caliber of anything in the Hitchhiker's series. I remember while reading it wondering how could all the reviews have been so good. I just checked fakespot, and it had an F rating with 92% low quality reviews as of April 25 [0]. I then had fakespot update the analysis, and it's now a D, with 41% low quality reviews [1]. So it seems like the fake reviews were bought to get things jump started, and now real reviews are catching up. Now that I think about it, it's probably a fairly common way for authors and/or their publishers/publicists to get the early sales and hype going.
[0] https://imgur.com/a/PWFTTbV
[1] https://www.fakespot.com/product/space-opera-7ea7cc4e-4bae-4...