In Minecraft, if a shulker box is surrounded by sand blocks, and a sticky piston pushes a honey block next to the shulker box. However, there’s an empty space below the shulker box. When the piston activates, the shulker box breaks and drops as an item.
This happens because the empty space causes the game to treat the shulker box as unsupported, leading to its destruction.
There is no bug here, you are breaking the shulker box with a another block moved by a piston (sand) which is an intended mechanic.