The changes relate to the interaction of the seller with the buyer and involve several additional restrictions. New rules are available here: 

https://sellercentral.amazon.com/gp/help/GQHQGBTD7XB7EECN

In general, Sellers, as before, can contact with the buyer only if it is necessary to complete the order or to respond to customer service inquiry. At the same time, sellers are forbidden to call, write emails or postal letters, or try to contact to the buyer with commercial purposes in any other way.

Requests for Positive Review and positive Seller Feedback are still banned. You can't send commercial or advertising offers, include any extraneous links (only if it is necessary to complete the order by the buyer and perform a number of other actions).