What is the max level of Curse of Binding?

The maximum level of Curse of Binding is I.

Curse of Binding

Max level ITreasureJavaBedrock

Quick answer: The item cannot be taken off an armor slot unless you are in Creative mode, you die or the item breaks. Items without durability and elytra only come off if you die, so removal is impossible in Hardcore. A grindstone does not remove it, and mobs are bound by it too.

Applies to

Armor, elytra, carved pumpkins, heads and turtle shells (anvil or loot).

How to get Curse of Binding

Treasure enchantment: not available in the enchanting table
Fishing, librarian trades and structure loot
Combine in an anvil

Best uses

Rarely a good thing to keep. Check enchanted loot before you equip it.