I noticed this recent problem with the water making some area of the land transparent. It's about a week ago basically. IF I try the version from 3.2, it does not work anymore.
If I remove the soil from the refraction with: water.addToRenderList (ground); it works, but the water is not pretty.
https://www.babylonjs-playground.com/index.html#1SLLOJ#517
If I try with the previous Stable version, it tells me BABYLON.WaterMaterial is not a constructor.
On my project, it makes half of my land transparent.