Why are we seeing: "We apologize but Amazon has noticed some unusual reviewing activity on this account."

My dad saw this when trying to review a product. Here is the entire message:

We apologize but Amazon has noticed some unusual reviewing activity on this account. As a result, all reviews submitted by this account have been removed and this account will no longer be able to contribute reviews and other content on Amazon.  If you would like to learn more, please see our community guidelines. To contact us about this decision, please email [[email protected]](mailto:[email protected]).

I just sent an email to [[email protected]](mailto:[email protected]) and am waiting for response. He might have written 2 maybe 3 reviews that he knows of. Has anyone ever seen and maybe their account had been compromised?

Thanks in advance!