If you walk into a block at your head without a block at your feet you'll clip into that block and if you're in survival you'll suffocate. You can easily get out if you walk out of the block and there isn't a foot level block where your walking. All you can see is the block texture further out than the block you're in, therefore you can see some of other blocks next to the block you're in. It's not a huge problem but it's quite wired and probably shouldn't be in the game.