Armor piece from loot chests can have invalid enchantments

Found a leather helmet in a woodland mansion with the Efficiency 1 enchantment, This should be impossible since Efficiency is an invalid enchantment for armor pieces. This also cannot be made with commands in bedrock. The world is loaded with beta and gametest feature activated.

Seed: -1561457299

Teleport to the coordinates: 17428, 66, 16800

Apologies if this has already been reported, i did try and search for a similar issue in the site before reporting this but found none.