I didn't zoom and enhance CSI style like the OP but yes there is a gap. I haven't experienced any water intrusion into the cab but over time who knows.....This is a 22MY year XLT.
I read the thread the OP is talking about. It was about mold and wet in the cab under the floor mats I think. It went from there to speculation as to where the water was coming from. The. Third brake light as well as other places were mentioned.