I was playing in a new world and I noticed some unusual chunk lighting issues underwater, as seen in the attached screenshot. There is no sky access, yet it is lit as if there is.
It seems confined to two open areas underwater in the same chunk.
Java Edition 1.20.2
Seed: 9001033045073773071
Location: -1105 60 114
Can't reproduce in 23w45a. Can you try optimizing the world to see if that fixes the lighting issues?
[media]Singleplayer -> [world] -> Edit -> Optimize World