Bug was found on MAP31 of TNT: Evilution. Engine renders/displays some sector polygons (lines and ceilings) in top of fake water, but they must not be displayed.
Here’s how it looks: https://youtu.be/aI_oepQ37ik
P.S. Sorry for low FPS, I’m out of home now with Intel HD Graphics laptop.
Does this happen in 2.0.4 Final?
Unfortunately, it looks like a Vanilla rendering "hack", which GL ports often hack around to look correct. I will try to look into it, but no promises if I can get it fixed