I have a 2019 RST with the same issue. I will be bring it back in for the same issue for the 3rd time. First time they tried to bandaid it when I was told it was being replaced ( siliconing or butyl from the outside) ?. Second time I was assured that they would be actually be replacing the window. Third time all parties were irate. Dealership, body shop, window shop. Long process seeing as the headliner and cab spoiler need to be removed to access the window. Yesterday when I took it in for them to check for the third time and I brought it into the shop so they could hit it with the wand with the dealership and mechanic present so they could see and the mechanic said he thinks it's actually coming from the cab spoiler. Must not be sealed properly but it comes in at such a weird spot. Driver's side top right hand corner of the rear window. It comes in from behind the read window rail corner. Completely dry if you run your finger through the track but where it attaches to the window it makes a slow stream inside. Mechanic said I was lucky because one guy had it flood into the cab and destroyed his head liner. Let them know it could be the cab spoiler so you guys dont have the same headache IV had driving a loner for over a week total.
