Odd artifacts using Zylann heightmap plugin (noob question probably)

Godot Version

4.1.2

Question

Hi! I am a Godot noob, playing around with Zylann’s heightmap plugin. I am seeing some strange artifacts in my imported terrain, and just wondering if it is obvious to anyone why this is happening? My heightmap is real-world data collected by satellite observations so it is possible the artifacts are in the data, but they don’t seem to be there when I create more straightforward visualisations so I don’t think that’s it.

Here are a couple of screenshots to show what I am seeing:

I am saving the data as raw 16-bit ints, scaled from 0 to 32000,. Am I doing something dumb there? I tried a few different scalings but it didn’t seem to make any difference.