If the store has the Shippo or Uber Direct integration turned on for your delivery method, the address is validated (and, for Shippo, a live shipping rate quoted) through that provider instead of the built-in zip-code/route map. A failed provider validation blocks delivery outright for Shippo; for a successful Shippo validation, the order still flows through the normal zip-code rule afterward to finish setting up the delivery details. Uber Direct works a bit differently — on a successful validation it confirms delivery directly without also running the zip-code check.