Chosen Solution
There are mostly white but other coloured stripes as well on the screen, that come and go based on what’s displayed. The phone hasn’t taken any major damage recently nor suffered a serious fall. The stripes appeard out of nowhere and I don’t think the LCD is faulty/damaged.
P.S. It’s my friends phone, that I’m trying to fix, not mine. I’m not a k-pop fan.
Certainly looks like a faulty/damaged LCD. Try a replacement screen to see if that solves your issue. The repair is easy enough to attempt yourself, just follow this guide: iPhone 6 Screen Replacement The iFixit screen is around £60, so it is also going to be cheaper than replacing the device. All tools and parts you’ll need are listed on the repair guide too.
