Just had this problem!
Purchased a 2023 sportline beginning of November.
After a couple of days snow decided to give it a quick wash as I was heading upto Scotland the following morning.
Only used the hosepipe and took delight in washing off a far amount of snow from the bonnet and off the roof.
Imagine my dismay to open the boot to see a large puddle of water on the parcel shelf!
Straight onto the local dealer from whom where purchased it from.
Couldn't take it straight back do to the trip to Scotland until the following week.
Initially they couldn't find any leakage. Provided photographs (again!) Accepting it was leaking they struggled to locate where. Car was with them for over a week eventually discovered that the drainage system was blocked. Only advice given is to have it cleaned regularly. WD40 around the seal and use it regularly as according to them it helps keep the drainage from blocking!
So wife's not to pleased as we are driving around in December with the sunroof open 😀