The seal on the 3rd brake light looked like it had been chewed on by a dog and was sagging.
A new third brake light with an improved seal will fix the issue. The truck is at work with a fan on it drying out the carpet and padding underneath.
So my ride tonight is a bright red 2012 Impala LS they needed driven to make sure the CEL doesn’t come back on. The 3.6 is pretty quick and it’s comfy but eh, I want my truck.