The bug

24w44a finally split away all of the baked slot icons from the inventory textures. However, Programmer Art's slot textures may have been left behind, as they now appear to be using the new textures.

This affects some things such as the brewing stand and rideable mobs, as well as the enchanting table not using the "old" sprite for lapis lazuli.

How to fix

I assumed fixing this would be similar to MC-265265 (which is an easy fix by the way). However, it seems like the sprites are merely misplaced:

• the saddle, potion and horse_armor slots are in textures/gui/slot, rather than textures/gui/sprites/container/slot
• the lapis lazuli slot is still in the items directory, rather than the one mentioned above

Moving these files accordingly should resolve this problem.