I have a moto g4 plus and when I woke up today i saw that my right side of the phone is entirely covered with shadow of previous notifications I restarted the phone it won't go away input is working fine though Here is a pic look closely to the right side https://s.yimg.com/hd/answers/i/fa3a64276a4b4489b0bc90f445aeddd1_A.png?a=answers&mr=0&x=1481432255&s=7587f59cf4fbfffe6d680c365028ae61
The Moto G4 has an issue with screen retention. Basically when something is on the screen in the same place for a long time, it will "burn in" and leave an after-image for a few minutes.
It seems that Motorola shipped the G4 with a screen that doesn't deal with screen retention very well, and it especially happens when the screen is warm.
In the end I had to flash a custom kernel (ElementalX) to the phone and use CF.Lumen to reduce the "Daytime color filter" settings to R=0.769,G=0.769,B=0.769 with the KCAL driver. This reduced the chance of screen retention significantly for me in exchange for screen brightness, but it still happens when the screen gets really hot.