Sometimes, and really weirdly, everything basically goes weird. Flowers flicker, you can see inside glass blocks. Spectator mode goes really weird, its like you don't see the other side of blocks, but you can see the other side of the block, so you can't see inside anything. I can't really explain it, but look at this picture: 

Here's me in spectator looking at a geode:

Weird... but what's even weirder is when I pause or go into chat in the game everything fixes after a few seconds. But when I leave chat it goes back.