The black boxes in the address block mean the address went through our National Change of Address (NCOA) process. If you ever see the primary and secondary lines blotted out but not the city, state, and zip (without plus 4), that likely means it has gone through NCOA. See more information on this here.
For context, USPS requires that we reference a database that they compile and maintain which captures all requested change of addresses. Our Production teams reference this list to verify addresses before handing them off to the USPS for fulfillment.