The Bug
1. The texture map for the magma cube was cleaned in 23w31a, but a few sections of unused pixels were missed.
2. The bottom face of the model cubes had been removed.
Unused Pixels
unused highlighted in red
used but removed in blue
Fix:
Restores the removed pixels, and removes unused ones
[media]Linked issues
relates to
Attachments
Comments

This issue clones MC-242092

This got fixed along with MC-225367. The bottom of the lava cube was also returned.
Confirmed, additionally the bottom face of the lava cube was removed, which was wrongly indicated as unused in the original report (which I stated to be the case in its comments).