trigger.item.hand.nbt.KEY and other NBT related placeholders break with the 1.21+ changes to item data.

Using the item info debugging tool in Mythic you can see the data is still present, but with how the structure changed, any placeholders that worked in 1.20.4 return UNDEFINED in 1.21+. 1.21.1: [Legacy attachment omitted] 1.20.4: [Legacy attachment omitted]