Better Skylight

Improves how minecraft handles sky light to take into account that objects high up doesnt cast as prominent shadow as objects low to the ground

Vanilla skylight: platforms at varying height casts similarly sized shadows

Better Skylight: shadow influence decreases as the platforms get higher up

its not quite the same as a shader as instead of just changing how the light is rendered it changes how minecraft calculates light level making it also affect mob spawns

The mod was made for fixing an issue in my modpack. With sky islands in this case spawning over a village it casts the entire village into darkness altough its high up in the sky

so therefor a change needed to be made to how minecraft calulates light level, and altough not perfect this is how that exact same area looks with Better Skylight

theres still a shadow but its much less overwhelming the area.