Resolution: Cannot Reproduce
It used to happen on older releases but I just ignored it then but see it happening more again now.
What I'm experiencing is the light from torches bleeding across the screen. Not the actual light but the actual image of the tips of the torches.
They look like yellow lightning bolts shooting across the screen coming from the edges of the screen where a torch would be. It's entirely random.\
I don't have a way to record video to show you, but I'll try on my old iPhone4 (Yes, I know it's old) whenever I have the chance and it starts up bad enough to be able to capture.
It doesn't stop the game play, it's just sometimes a bit distracting and ugly.