If you leave the "Inbound with original packing" option checked, your item will keep the boxes that the seller used to ship the item to the agent.
This will increase the weight and the shipping price. Under normal circumstances, there's no reason to use this, as the agent will provide a fitting packaging.
When you click confirm, it is unchecked. So it's a sort of reverse logic, click "confirm" to uncheck it and get rid of the seller's box.
Before this service was introduced, that's how it always worked and it worked just fine. You can see this as an extra feature introduced by Superbuy for people who want the agent to mess with their stuff as little as possible.
added: 6/26/2023