Falling block upon world generation might cause dark spot with client light 0

Can confirm.

After doing some testing, I found that this bug was introduced in 24w45a (at least at the specific location mentioned in the bug report).

I reproduced this issue in 24w45a but can't reproduce it in 24w46a.
Btw, there is gravel in the place of the block with zero lighting, which immediately falls when you teleport to this place. Maybe this was fixed as part of another fix, somehow related to falling blocks..?

I can reproduce this in 24w46a.

Found similar things in 1.16 (but not in 1.21.3)

Edit: Seems to only happen sometimes with Fancy + Smooth Lightning OFF

I did reproduce this with Fabulous and Smooth Lighting ON.

Nevermind still happens

Looks like there is a case where this doesn't happen. I wonder if it has to do with how the chunk loads.

I then clearly noticed and saw that there's a gravel block that falls off around that time, into the water. I wonder if it ever falls before the chunk loaded or something.

Do placed blocks even have a light level at the location they're placed at? Is there some async like behavior where the block was thought to be solid but at the same time the solid block started falling, so then it just got client light 0?