Fully tilted big dripleaves render slighty too dark whilst having smooth lighting enabled

The Bug:

Fully tilted big dripleaves render slightly too dark whilst having smooth lighting enabled.

Steps to Reproduce:

• Enable smooth lighting.
• Place down a big dripleaf.
• Stand on it so that it tilts.
• →  Notice how the fully tilted big dripleaf renders slightly too dark compared to a slightly tilted or untilted one.