Here is what I found with extensive research and tinkering with the doors. Main reason I messed with them is I also have what seems to be excessive road/wind noise that seems to be coming from just behind my head to the left. I have done everything with that sliding door and nothing improved the road noise. Anyway, long story short I may have a fix for you because I was also experiencing the groaning type noise or whatever you wanna call it. I believe it was the weather stripping. I would recommend conditioning it with a automotive weather stripping lubricant. That instantly removed any noises I had coming from the door. It didnít have anything to do with the door panel itself.
Hope this helps.
2017 Cadillac ATS 3.6 awd Premium, Phantom Gray, Carbon Black package, Recaros
2017 Pacifica Limited, bright white, black/deep mocha, AST, blu-ray, 20Ē wheels, HK audio