I was at my endermen farm and sorting through some of my items in shulker boxes.  I placed a shulker box so that it opens up sideways, and when I opened the box, it pushed me backwards.  However when I closed it, the I fell through the platform of my enderman farm into the void.

I just expected the box to push me backwards a bit and that would be the end of it.

What happened was I ended up falling through my platform.

To recreate this, you need to go to the end, make a platform at y=0  and then place a sideways shulker box (this means the shulker box would be at y=1 on top of the platform).  Open the shulker box while you're right next to it so that it pushed you backwards a bit, and then when you close the box you should fall through the platform.  This works on at least spruce leaves, oak leaves, and oak planks.

Very important that it's in the end and at y=0, or else the bug doesn't happen

One picture is before opening the shulker box and the second picture is falling through the platform after the shulker box moves you.

Update: this also works if the shulker box pushed you when you are on top of a chest (anywhere)