When you walk over soul sand the light is completely dropped you block light become 0 and your skylight becomes 0 and even when you surround it with light sources it still will not have light

Steps to Reproduce:
1. Place Down Soul Sand
2. Walk Over It

For the photos they show when i'm over the soul sand and when i'm not over it and the light levels also for the nether photos the first one is when i'm slightly above the soul sand and my light level is 14 and the second one is when i'm on the soul sand and my light level is 0 this also proves it's not just placed down soul sand naturally generated ones can also do this. hope this helps fix a bug.