Vault's item model is hollow

At a glance, the vault seems to use a similar model to the monster spawner or the trial spawner, but there is a difference: The gray base is not just a flat texture on the outside, but is actually a visible element on the inside of the model.

However, the vault doesn't display any of its inner faces when held or dropped, which is inconsistent with the block as it exists in the world and with how it is displayed on Java Edition.