Lighting issue persists, where certain chunks are totally unlit, and all light sources provide no light, manually fixable by replacing lightsources, or placing block on/next to said lightsource.

Haven't noticed it anywhere but in the Overworld, but seems to occur when loading into the overworld from the End, or the Nether. Doesn't occur everytime, so isn't easy to reproduce.

Unproven theory: Seems most often to happen to slimechunks, and those slimechunks don't seem to be spawning slimes very often or at all (still testing). But when I have the darkness lighting issue, it always seems to be the slimechunk that my base is located in, and surrounding ones are fine, and another user has noticed the same thing. Could just be coincidental though.