When growing oak ( & sometimes spruce) trees that generate with leaves too close to the ground, you not only suffocate, you are stuck in the leaves until you break yourself out.
I believe that leaves from growing trees should push the player out of the way instead of trapping the player.

Possible Resolution:
Instead of making these blocks(leaf blocks) only suffocate you, make them push you out of the leaf block's boundary when you are inside them(again only for leaves from growing trees).