When mining blocks it sometimes takes a moment for the blocks to unrender.
The hitbox of the block disappears, the item drops and you can walk through them (which makes it possible to see below the surface)

What I expected to happen was:

The block unrenders as soon as I mined it and I can see the blocks behind it

What actually happened

The blocks stayed there for a short period of time
Youtube video
In this video the blocks unrendered really quickly, but sometimes it takes 4 or 5 seconds to happen

How to reproduce:

-Go into survival mode with a fast shovel
-Mine dirt blocks