If a Shulker Box is nearby a live shulker, it mimics the shulker's opening and closing, even in the player's inventory

When nearby a live shulker, a shulker box will open and close along with the shulker, both in the player's inventory and placed in the world. You can still interact and place items in the shulker box. When there are no shulkers nearby, the shulker box acts as normal.

Affects 20w45a. See video.

As far as I can tell, this is purely a visual glitch.