Right. Well, I found that a Gaussian Blur removes artefacts nicely too… but then the problem is that at least in the GIMP implementation, it leaves color banding. There must be a way to lerp (interpolate) color values to leave a smooth grading… but as far as I can tell, most people suggest using noise to fix color banding. I somehow find it hard to believe that there’s not a function somewhere to interpolate bands of color values…
I had a look for any blueprints that smooth via lerping vertex heights, but it’s not so obvious. There’s also some potential in using weight layers… but I haven’t dived down that rabbit hole