The Bug:
Cave vines can generate into water when starting above water and the length is larger than the distance to the water surface.

How to reproduce:

Seed: -729051142556713127
Coordinates: /execute in minecraft:overworld run tp @s 891.78 -29.37 -956.01 -359.55 30.45

Due to MC-219200 seed and coordinates may be incorrect sometimes

Cause:
The "allow_water" setting of the "minecraft:block_column" feature is behaving differently from expected: If set to false the block column can generate in air and water; if set to true the block column is generated independent on any blocks and generates through stone.

Expected Result:
The Cave Vines wouldn't generate into water