How to solve normals artifacts? I tried to model something like a cog. I created one tenth of the cog, mirror modified on 2 axes and added a circular array modifier to get the final result, using the merge option.

When I import the final model in Substance Painter, it looks as if the normals were off on the big flat surface. At least that's how I interpret it:



Any ideas what could be wrong here?

I checked, and all of the selected vertices below are on the exact same Z. Not their median, but the individual values.



If I simply create a circle mesh and fill it, I get a perfectly flat mirror surface:





EDIT:

Shading entirely smooth or flat doesn't seem to influence this issue:
It seems to be an UV issue. I mapped identical parts of the cog to identical areas on the UV map. Substance Painter doesn't seem to like that. Unreal Engine doesn't seem to have this issue. I now applied all modifiers and smart UV unwrapped and I'm finally having no artifacts.