Ebay introduce new changes connected to Business Policies. As result, a seller can start to receive warning or error related to this change.
This is related to new ebay requirements https://go.developer.ebay.com/coming-soon-business-policies-opt-inopt-out-will-be-enforced
So for a seller that just get the warning. Ignore it. For a seller that receive an error and can't list a new item, please sing out from business policy feature.
More information regarding business policy you can find there (including how to include/exclude it for seller account).http://pages.ebay.com/help/sell/business-policies.html
PrestaBay 1.7.x, 1.8.x, 2.6.x, 2.7.x include all support for ebay Business Policies.