Certain worlds render biome fog darker than intended

Hi,

I've noticed sometimes the biome fog colors from my datapack "Incendium" don't properly show up - they render much darker than they should be. This has been happening since 20w28a and appears to be a world issue.

I have attached screenshots as well as a world that is affected by this issue.

This is a very odd issue which has affected me intermittently; it tends to happen with specific worlds and persists after a game restart.

To reproduce the issue:

(1) Load the world Incendium-BAD-FOG.zip

(2) Navigate to a 'starmute:quartz_flats' biome

(3) Observe the color of that biome's fog