I noticed that players are using packages to carry a lot more items than intended and I think this is a big balancing issue, as this allows carrying around up to 6 times more stuff.
To prevent this, unsealed packages should not be allowed to hold items when put pack in the inventory.

Will looking into changing this.

Same with Present & Envelope

Closing due to Shulker boxes

Opening again. Will disable shulker boxes being added into said items

Fixed in 06acace