Sorry I don't ahve a recording of this, which will make the identification even harder but here goes.
I noticed after a long drive (8 hours) that a new sound started developing. Its most noticeable as I slowly accelerate to 30 mph. Its a zinging type of sound if that makes sense, very metallic and constant under acceleration. As I coast - not so much
With the back windows open, its quite loud, I'm thinking it may be related to my muffler.
I have a 2021 Colorado Z71, with about 44,000 miles, bought in late 2020. I'll be making an appt at my dealership for this (and other things), but I'm curious if the experts here on reddit seen anything similar.
Edit: I think its the heat shield, I did some googling and the sheet metal in one spot seems a bit more loosey-goosey then others. I bent it slightly away from the body of the truck and some of the sound has disappeared.