This is a texture bug.

As I updated to 1.13.0.0...
I was in my survival world I was searching for the end rods.
I typed en- and it appears so I scrolled down to the end rods and as I do that I find a visual glitch that the textures of my inventory menu is flickering to dark and light very fast . I tried to do it another time but it didn't happen. I tried logging off and on my world and it happens again.

How I did this:-
1 open a world(survival or creative)
2 open inventory menu
3 choose search menu
4 scroll down to it.

Voila you found it.