The Bug
When glow lichen is on top of a shulker box (no matter the angle), it can still be opened.
Steps to Reproduce
Place down a shulker box facing upwards.
Place down a glow lichen on top of the shulker box.
Attempt to open the shulker box.
❌ → Notice how shulker boxes can be opened when blocked by glow lichens.
Expected Behavior:
The expected behavior would be that shulker boxes cannot be opened when blocked by glow lichens.
Can confirm in 21w13a.