1000000000000x correct !!!
Every time someone new comes to this thread it seems like the same story. "window leaking, dealer said it's the brake light, nothing to worry about, we'll reseal it, move along"
Does it not seam odd that GM is telling dealers to tell customers it is just the "spoiler" or "3rd brake light" or "window seal" to de-escalate fears or attempt to calm customers AND not admit that the window frames are actually cracking. Even if you look at all the service orders when they do the repair, it says "found window leaking, sealed or replaced window per TSB". They won't put the words "cracked window frame" in the receipt they give you. Why? We have seen these cracks in this thread. They have either found no way to stop it or refuse to look into it. It doesn't take over two years to solve why a plastic item is cracking if you wanted to solve it. If someone can prove this wrong or if GM was willing to be transparent about it, I will happily eat crow. But it has been two years. Everything @OnTheReel said is accurate.
Don't take my words above as me hating on GM. I love my truck sans the leaking issue. Just be honest and transparent, it is not hard. It is what we teach our children.