Why are the 3 lines on my galaxy note 5 at the top right?

[AC Question]

So I have a galaxy note 5 for almost 2 years and something popped up on my screen lately. It was 3 lines on the top right of my screen and I don't know if it's nougat problem or just a problem on my screen.
It's not that bold but you can still spot it and it's like yellow - orange color.

 

[jasonandrews25788]

if they don't exist on any screenshot then it's a hardware issue.

 

[Tim1954]

Dial *#0*# to get into service mode. There you can check the hardware.