Wierd shapes on material

Hi All,
I’m working on a shader and I currently have it set down to just an alpha mask.
I started noticing these weird shapes - thought maybe my monitor was failing but they are actually rendered.
I’m sharing a couple of shots. they always seem to go in 4 pixel groups.

This is how it actually looks

It’s barely perceptible in reality, but I’m just curious as to what those may be.
The material has a single 0 constant in the base color and a tess multiplier with tess enabled but no world displacement applied.

It seems like some kind of a directional light issue. has anyone experienced this before / know what it could be?

Might be an idea to show the material setup. I just tried this and it’s pitch black…