I realised a crucial error! Slot locking wasn’t permanent. After an hour and a half of hard work I’ve managed to make slot locking permanent. Now whenever a slot is locked the slot number is written into a file that lives in the config file of minecraft folder. When the slot is unlocked it is deleted from the file. I had to spend a while making sure that it only locks slots when on Hypixel Skyblock but now when you join, it reads all the slots in the file and locks those slots.