The inner faces of mangrove roots darken when solid blocks are present nearby

The Bug:

The inner faces of mangrove roots darken when solid blocks are present nearby.

This issue can more easily be seen when smooth lighting is disabled but still occurs regardless.

Steps to Reproduce:

1. Place down some mangrove roots.
2. Place down a solid block directly adjacent to the mangrove roots.
3. Look closely at the inner faces of the mangrove roots.
4. Take note as to whether or not the inner faces of mangrove roots darken when solid blocks are present nearby.

Observed Behavior:

The inner faces are darkened.

Expected Behavior:

The inner faces would not be darkened.