For a long time I’ve known there was a visual glitch around waterfalls, but only today looked a little closer. It occurs only when reflections are set to “very high”. Waterfalls are then reflected by water in impossible ways. This produces a weird illusion of water flowing quickly upstream.
I’m attaching 2 examples. The first one a player sees is on his way to fight Viloth.
Another, more pronounced occurrence I saw on the way to Hallowed Hill.
I decided to report this even though it’s unlikely to be fixed at this point. Just like shadows = low not working properly. But maybe at least rename this reflections setting from “very high” to “too high”.