The Bug:

Paintings larger than 1x1 have unnecessary inner faces.

Steps to Reproduce:

1. Summon a large wall of blocks by using the command provided below.

   /fill ~1 ~ ~1 ~1 ~9 ~9 minecraft:polished_andesite

2. Place down any painting that is relatively large in size.
3. Switch to spectator mode and look at the painting's inner faces.
4. Take note as to whether or not paintings larger than 1x1 have unnecessary inner faces.

Observed Behavior:

Paintings larger than 1x1 have unnecessary inner faces.

Expected Behavior:

Paintings larger than 1x1 would not have unnecessary inner faces.