Custom enchantments disappear when you merge or rename items

Custom Enchantment Disappears When You Merge Objects.

Exemple :

Give Item with enchantments custom.

/give Hardel minecraft:diamond_sword{Enchantments:[{id:"minecraft:Test"}]}

Merge this item with another item in a anvil exemple with "enchanted book fire aspect".

Make a "/data get" and look enchantment "test" is gone.