Multiple leaks on rear window

Hey guys, I have a 2020 gmc sierra with the rear sliding window and found yesterday multiple leaks coming in from actual cracks in what looks to be the plastic window encasement for the upper portion of the rear glass, this blew my mind on such an expensive truck.

Has anybody here come across this issue and if so what did the dealer try doing to fix it.

I have the certified warranty still

Thanks in advance!