[This ticket has been merged into MC-262465 and therefore should be marked as a duplicate of it. The original contents are preserved below for clarity's sake.]

The bug

Thirty-six pixels of the cauldron feet texture are not used at all by the model, rendering them entirely unused. This is the case in both the default textures and Programmer Art.

The pixels first appeared here in release 1.8's development, likely due to changes to the cauldron model around this time, however they ultimately went unused. The Texture Update did not remove these pixels for some reason, and still uses the same shape as the old texture, with nine unused pixels at each corner.

How to fix

An easy fix - just replace the vanilla cauldron bottom texture file with the one attached, and replace Programmer Art's with the fixed Programmer Art bottom texture as well.