Apply the attached data pack to a world, and open the beacon UI. Then attempt to place a netherite ingot inside the payment slot. As expected, the slot forbids placing it inside. Then add a copper ingot, and note that it's accepted as a valid payment. This is to be expected, as the data pack replaces netherite with copper as a valid payment item. Despite this, the item sprites shown to the left indicating valid payment items remain the same - the UI falsely infers that netherite is still a valid item to use in beacons, and omits copper.

Expected behaviour would be for only items which can be used in beacons to display here.