The bug

If you fall out of the world, when you take void damage you can see chunks that are un-rendered because of the damage tilt. Happens in other situations in which you take damage as well but this is the easiest way to reproduce it.

Steps to reproduce

1. Fall out of the world in the overworld
2. Face like northeast (any intercardinal direction works)
3. Watch chunks flicker in and out of existence as you take damage