The hatch latch is loose and rattling

If the vehicle is under warranty, get the dealer to look at it. If not, you would need to check the door latch striker adjustment. The latch works in two steps and if the hatch is not correctly adjusted, it can lock only at the first step resulting in the looseness.

Secondly if the latch is locking all the way, the striker could have worked itself loose resulting in slack when hatch is closed. The problem can also be due to plastic covering of the striker being damaged.