[Dupe with Show Item Plugin] Right click opening a shulker in someone else's inventory let's you take their items and doesn't update contents.

If a player show's their inventory you can right click open their shulker box and take items out of it without it updating their shulker box contents causing the taken items to be duplicated. The inventory title is [playername]'s inventory but because it shows their name you can't blacklist the inventory to prevent opening their shulkers.