[Arrow768]

Thats how its meant to work.
The item is removed after the expiry time from the inventory.
If you want that the player gets restored to his original size you have to add a timer to the plugin that restores him to his original size (you could add this as a json parameter so you can modify it easier).
(You might also want to set the expiry time to 0 and remove the item after the user has used the item).