My wife had a similar issue on her 2016 mustang. Rear window was replaced and the top brake light had a leak. Dealer instantly denied the warranty. She took it to a different Dealer and they replaced it no questions asked. It was actually a faulty brake light. I don't remember full details...
Its going to feel a bit different because its heavier but trust me. It doesn't disappoint. Im hitting 80 mph like its nothing.
Also the exhaust will break in around 1500 miles or so and you'll notice its gotten louder.
Mine is only missing the ford built tough. Everything else is fine. I heard it was glitchy at times so not really worried about fixing it but it just odd its not set.
I was about to get the 26 lariat but then I looked at raptor and saw how much better the interior was. My wife noticed too and told me to go with the Raptor.
That's pretty good. Main reason I wanted a lariat in the beginning was because of the keyless entry and start. Often find myself with my hands full and have to reach my hand in my pocket to unlock the door. I have to put stuff down just to do that.