I believe this is a shader bug in 4.22
Maybe someone can verify?
This happens with Translucent, Forward Shading, and Tessellation.
To test, you can snag the materials from Alan Willard’s water planes
And convert the ocean to translucent forward shading.
It won’t be the same / it’s not a Gerstner wave algorithm, but I get the issue on that map as well, albeit to a much lesser degree over the fact the material is dark to begin with.
If needed I can put my shader and a plane in a project and share as well. I just need this to be solved, either by a bug report/waiting for a fix, or by changing the material in a way that works if this happens to be an engine limitation and not a bug (not sure why, base color view looks fantastic even if not transparent)
Here are the screenshots:
Unlit.
Lit
Base color + tessellation only.
Full details here
https://forums.unrealengine.com/development-discussion/rendering/1659887-wierd-artefact-on-tessellation-shadows-how-do-we-get-rid-of-this