Shulker box generates loot from loot table when broken

The bug

Breaking a shulker box with a loot table causes it to generate the loot despite it not being opened.

How to reproduce

1. Use the following command to place a shulker box with a loot table

   /setblock ~ ~ ~ white_shulker_box{LootTable:"chests/simple_dungeon"}
   

2. Break the shulker box
3. Pick up the shulker box item and hover over it