both of the following biomes water surface is unable to have a custom water surface color

Birch forest mutated

birch forest hills mutated

you can use the following pack underneath to see that the water surface color does not change. (ignore the fog change as thats for another bug report)\

steps to reproduce

go to tall birch forest or tall birch forest hills and see that the water is not changed unlike all other water

expected results is that the water is the same as all other water