Smooth lighting doesn't work on blocks that emit light

The bug

Blocks that emit light do not receive smooth lighting, so blocks that emit low light within the radius of a higher light source are not smoothly lit.

Steps to Reproduce

1. Install the attached resource pack below

2. Navigate to a dark area

3. On the ceiling, place a platform of Respawn Anchors

4. Below one of the Respawn Anchors, place a lantern

5. Place one Glowstone in each of them

Here, the bottom face of the respawn anchors will not have smooth lighting.