Whenever you email firstname.lastname@example.org for sending in your FTP details or asking about a billing problem, when someone replies, it also sends a link to rate them.
The faces on that page are not accessible, I generally go with the rule that good is on the left, but I really do not know which one I am choosing when my screen reader will not read them.
I understand that this is a third party provider, but they have your logo on their website, and you might want to get it fixed. Also, when you click on the powered by link, instead of opening their website in a new tab, they open it in the same tab driving your customers away from completing the rating.
I can give you an exact link if you first mark this private, otherwise, I have given you as much information as I can.