Rainwater in spare tyre well

Hello everyone, I’ve got a 2015 A3 Sportback and recently noticed the lining in my spare wheel well was very damp, although the main boot area is completely dry. I took it to a garage who said it was likely the vents behind the rear bumper getting stuck open. They supposedly fixed it, but the issue is still happening. I’ve checked behind the rear lights which is dry, and the rubber seal along the bottom of the boot looks fine as well. Has anyone else come across this before?