Snow (layer) doesn't take light level from block below into consideration

Snow melts when the light level is high enough, however, it does not melt based on the light level of the block below it.
simple test:

1. /fill ~-16 ~-1 ~-16 ~16 ~-3 ~16 stone
   /fill ~-15 ~-1 ~-15 ~15 ~-1 ~15 glass
   /fill ~-15 ~-2 ~-15 ~15 ~-2 ~15 glowstone

2. run this twice with ~ 1 second in between /fill ~-15 ~ ~-15 ~15 ~ ~15 snow
   → ❌ Observe no snow melts at areas which remained covered after the first few ticks

3. Break a single snow layer
   → 👍 Observe snow now melts around the broken block