They have the texts of the Trump employees talking about storing the boxes in the bathroom when they first arrived.
The pictures of the boxes, are as they were found, when the FBI arrived.
The Trumps were watching the whole FBI search through the boxes over the security cameras from New York, and have threatened to release the footage, but haven’t yet, possibly because it’s not in their favor.
All of these points are established fact, that no one except uninformed Trump supporters are disputing.