I had an issue today where I was growing some 2x2 spruce trees with bonemeal to get a large quantity of spruce logs. However, I was standing close to one of the trees and when it grew, the leaf blocks went all the way to the ground and my player character got stuck in the blocks. I could not break my way out of the leaf blocks, nor could I dig my way out from beneath me. I had to exit the world and restore it from a backup from yesterday.

During my farming of spruce trees today there was another tree that also grew with leaf blocks all the way to the ground, thankfully I was standing further away while applying bonemeal so I didn't get stuck again. So it wasn't a complete fluke, it does happen occasionally.

The work around for this is to make sure you stand back from the saplings while you are hitting them with bonemeal so that you don't get caught in the leaves. The code should probably determine if the tree is a 2x2 then make sure that the leaf blocks start appearing at least two blocks above ground level.