1) Added protection against shulker boxes with invalid data, these boxes appear to have about 700ish items worth of NBT data in them, and if a player has several of them in their inventory they are unable to log in. This is a lot like the sign/book ban however the shulker boxes alone appear in game to be perfectly fine. These boxes can also be dropped on the ground effectively "book banning" anyone who tries to log in near them even if they don't have them in their inventory. Before IllegalStack can detect these shulker boxes you'll need to have https://www.spigotmc.org/resources/nbt-api.7939/ Installed and running on your server! Sorry about needing a secondary plugin however this exploit can potentially be done on any version with shulker boxes and requires a LOT of NMS code to make it cross version compatible.

2) Added protection against the Hopper + Dropper/Dispenser loop dupe. I have been unable to actually reproduce this on a live server however I have received several reports that is is working in 1.14.4 both paper and spigot. Hence this protection can detect a hopper/dropper loop and break the machine.

3) Added an option for FixIllegalEnchantments to allow OP's to bypass the check. Thus opped players can create items with otherwise Illegal Enchantments as long as this option is turned on. If a regular non-op player takes the item, it will be fixed as usual. This protection is OFF by default.