My iPhone 6 plus has white smudges on its screen?

I got it three months ago, and is in pretty good condition. But today, I noticed these white dots and streaks of light on the bottom of my screen. The home screen has it. But if you go on other apps, it disappears like it was fixed. As far as I noticed, it only shows in the home screen and while I call someone.

I screen shot it, and it's still there, so I know it's something internally… But I'm not sure if it's fixable? I think it was caused when I accidentally left it in the sun, and it overheated. But I immediately placed it in the shade after it notified me. Would it have caused these white spots?

I mean it isn't really causing a great deal of problems, but it does bother me. Will it worsen over time? My iPhone 6 plus has white smudges on its screen

Oh god. It is fixable. But hey, not worth to fix it. Change your background to white color and you won't be able to see those white areas