This bug was discovered on and off the realm.

Player will walk/ levitate into solid blocks even when I'm the only player on the server/ realm. Found to be a more prominent bug in slabs. When levitated my a shulker, the player will suffocate in the ceiling like sand or gravel. The player can also walk into the leaves of low trees. In the most recent interaction with this bug, the player was struck by a shulker, levitated into a solid block above them, but didn't suffocate. Player broke the block and continued to levitate and when I fell I deployed elytra and glided to the ground. When I hit the ground I died as if I had half a heart of health. (Elytra part couldn't fit the file size)