I did go to one of the GMC dealers nearby a few months back, and explained the issue, they could tell that I had the windshield tinted, but asked me if I did anyway, when I said yes they immediately said this is why I was having the issue. Welp, replacing the ambient sensor proved them wrong. Since replacement on Saturday, that day was sunny, and overcast, Sunday was mostly cloudy, and today was all sunshine. Only the DRL's were on as they should be during the day, then when it got to be evening and the sun was all but down, the headlights took precedence as they should.