How do I make items unstackable?

[CoderElias]

How do i make items unstackable? I am working on a fishing game where you have to sell stuff, but the menu breaks if you put two or more stacked items in it. I thought about maybe putting an invisible item lore with a variable that keeps increasing, but my sell menu doesn't recognise this item because it keeps changing the item lore. Does anyone know how to fix this?

 

[CoderElias]

I found a way to make an item unstackable but simply giving it a random generated tag, but because every item is different so I can't sell it. The menu saves the menu items to a list and looks if the given item is inside the list, but that method doesn't work. Idk how to go from here, so help would be much appreciated!