Online retailer Amazon has imposed a restriction on the reviews of the Prince Harry and Meghan Markle biography Finding Freedom after the company noticed "unusual activity" on its website. 

The book charting Harry and Markle's royal exit, which arrived in stores Aug. 11, has received a deluge of negative reviews in its early days on sale. Since then Finding Freedom is trending more positively.

Finding Freedom, written by Omid Scobie and Carolyn Durand, has 66 percent five stars and 18 percent one star so far to date. The Daily Mail revealed fans of Harry and Markle mobilized a campaign to increase the book's ratings. As a result, hundreds of reviewers raved about the book - posting comments like "an unbiased read" and the most factual coverage of the royal family. 

But, fans of Harry and Markle were reportedly prompted to post the reviews to outshine the negative ratings and the promotion of another book. According to Fox News, the first 10 reviews of Finding Freedom touted a different book about the Duke and Duchess of Sussex. These shoppers said that the book was a puff piece, or fan fiction, while Lady Colin Campbell's Meghan and Harry: The Real Story was the real deal. 

Campbell is a critic of the Sussex pair and has openly slammed Finding Freedom as a work of fiction. The British aristocrat said Harry and Markle could have been the most revered royal couple but they failed because of their decision to quit their roles. 

Her book on the duke and duchess came out in June, months ahead of Finding Freedom. She also wrote a biography on Princess Diana. 

The Daily Mail reported that Amazon placed a notification of the review restriction to "only verified purchases" of Finding Freedom. However, the book is a top seller on the retail site and internationally. Scobie said on Twitter that the book had made it to The New York Times best-seller list. 

Harry and Markle said through representatives they didn't collaborate or sit down for interviews with Scobie and Durand. However, the authors had access to at least 100 of their closest aides, friends and workers.