googled the term cloud patch.
that appears to be moisture in the layers of the LCD.
if its moisture causing the issue, treat like a wet phone, seal in a bag with rice for a while (couple days) and see if it improves
It stays when I scroll. There seems to be a dimmer patch. Wiping the screen doesn't fix it. I'm not sure if it's screen damage or something. My girlfriend used it for some gaming and apparently it was "there before she started playing" ....