Iphone 7 Plus screen problems.

Hi, first of all sorry for my ''almost bad'' english ^^

I've got an Iphone 7 Plus 2 weeks ago and I have 2 problems with my screen, one disappeared and the 2nd one is still here but it's not visible everytime.

1. The 1st problem might be because of the latest iOS update or because today the temperature dropped below 0*C ( -7*C actually) ,my screen became very dark on some areas, the green on my messages was kinda dark, when I tried to increase the brightness my screen edges were bright but the rest of the screen was dark and it was very noticeable, it was like a inner glow effect coming from the edges of the screen. Also, every transparent or grey surface had some white spots, bright spots, best way too see them was using the 3D touch. The phone was exposed around 20 minutes to cold but when I came back to 21*C after a few minutes the screen went back to normal.White dots came back again but then they disappeared. This is the first time I have seen this issues in 2 weeks.I have tested the screen with Dead Pixel 2, no dead pixels here, no black spots, nothing.

2. The 2nd issue is a dark trail following my finger when I scroll, it's visible only a few seconds and then it's gone. From what I have tested, this problem appears when the phone is cold.The screen has no problem when I am inside the house for example.

Is this normal iPhone behavior ?