I saw a message on Facebook, alerting me to a petition on Change.org. I think you will be interested, and I encourage you to sign it.
Amazon has been accused of big brother tactics once again with their reviews. If their algorithms think you and an author know each other, the review will not be allowed.
Bottom line for me is that just being "Facebook Friends" does not make someone a close friend to someone else. Friendly, close interaction is part of the 21st century, but Amazon doesn't seem to care ... or notice.
The following is the text of the petition. You can find the petition at this link.