Items do not render inside boats

The bug

At some point in an undefined version, items stop rendering below the rim/inside a boat. They are completely invisible, leading to some very jarring visuals.

Note the same does not appear to be the case for minecarts.

Steps to reproduce

1. In an older version (e.g., 1.20), hold an item, have a mob hold an item in a boat, or throw an item into a boat.

   • Notice how the item is visible inside the boat.

2. Do the same thing in 1.21.5 or a later version.

   • Notice how the item is completely invisible.