Shulker Box cracking texture is inconsistent in color

The Bug

When breaking a shulker box, the cracking animation/texture it displays is inconsistent in color/shading. A part of the bottom of the shulker box appears darker than the rest.

This bug occurs for all colored variants of the shulker box.

See the image for a visual example.

How to Reproduce

1. Place down a shulker box.
2. In Survival mode, break the shulker box using no tools.
3. Note how a part of the cracking texture is darker than the rest.