Some Vanilla blocks cast ambient occlusion too harshly onto Vanilla blocks. The current known blocks to do this are:

• Cartography table

• Kelp block

There may be others: the full Vanilla palette has not been tested. Interestingly, these 2 blocks also don’t trigger culling against full and opaque Vanilla blocks, although such is out of scope of this bug report.

Demonstration

The 4 attached screenshots demonstrate this issue clearly. Other blocks cast ambient occlusion onto custom blocks proportionally to how they do Vanilla blocks, but these 2 produce garish dark corners.

If the related issue with culling should be inspected, simply enter spectator mode inside a cartography table or kelp block surrounded by full and opaque Vanilla blocks. The surrounding block faces will not be culled.

Reproduction

This example is taken from the behavior pack in the attached world for convenience. This world can be opened (in Minecraft Preview) for inspection or unzipped to access the code associated with such.