Chosen Solution
Had iPhone 6+ screen replaced last year. it recently started looking like this. I can press on the case and it will be normal for awhile. But then it goes back to the snow. Bad connection , bad screen?
It’s most likely a bad screen, if you want to confirm you can open the phone up yourself and check the screen connectors. There should be a metal plate on top of those connectors covering on the logic board. Guide to open up phone and additionally replace screen. iPhone 6 Plus LCD and Digitizer Replacement Where to get a replacement screen to DIY: iPhone 6 Plus LCD and Digitizer
