Buy Box suppression occurs when Amazon determines that all available offers for a product are priced unreasonably high relative to historical prices or Amazon's own reference price. In this state, the Buy Box is removed from the listing — shoppers can still purchase through the "See All Buying Options" link, but conversion rates drop sharply.
Suppression can occur even if only one seller is listing a product. It acts as Amazon's mechanism for discouraging price gouging. Monitoring for suppression events is an important signal for pricing teams managing large catalogs.