There is an issue when you column blocks out of the ocean from the bottom to 2 block above water that the chunk you are in lights up on the bottom of the ocean.
Related issues
Comments

Sounds like MC-128299. If not, please do attach screenshots.
There is an issue when you column blocks out of the ocean from the bottom to 2 block above water that the chunk you are in lights up on the bottom of the ocean.
Sounds like MC-128299. If not, please do attach screenshots.
migrated
(Unassigned)
Unconfirmed
Minecraft 1.13-pre1
Retrieved
Please provide screenshots.