With vanilla shulker boxes, you cannot place a shulker box inside a shulker box.
With this mod, you can put a backpack that contains a shulker box inside of another shulker, allowing for infinite storage.
A way to fix this is not allow backpacks to be placed inside of shulker boxes

Also, as a separate config option, please add the choice if you want shulkerboxes to be stored in backpacks.

Agree. Is there any issue with immersive engineering, actually addition, and other mods' infinite storage?@Tiviacz1337
Also, these kind of issue is just a word : матрёшка (lol)

Shulker boxes cannot be put in backpacks instead