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
Place down a shulker box.
In Survival mode, break the shulker box using no tools.
Note how a part of the cracking texture is darker than the rest.
Linked issues
Attachments
Comments

Yes, this seems to be a duplicate of MC-268537.
Would MC-268537 describe your issue? The cracking looks darker because the top and bottom of the shulker box are over eachother.