Here are two images: One from 1.20.2, other from 1.0
Both are vanilla instances without any mods.

To reproduce simply make a zigzag pattern down the ground, then let the water flow. But it also occurs in nature with water down the hills etc.

It is impossible for modders / resource pack makers to patch it because water and lava don't support custom models. Maybe best way would be to allow custom models? It'd make projects like Brickcraft better too (Since more detailed lava).

And no, shaders don't fix this either...