Oberlo Verified suppliers and Oberlo suppliers work directly with Oberlo, and their services are tailored to dropshippers. Therefore, they do not include any promotional material or order invoices in the packages.
If you dropship products from AliExpress, we would recommend adding a custom note to the suppliers informing that you are dropshipping because there is a risk that AliExpress suppliers will add some promotional material or order invoices in the package.
To add a custom note, go to Oberlo > Settings > Suppliers > Custom note. The supplier will see this message together with the order information.