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I’d like to leave my final solution here after exploring this issue. I’ve looked through many tutorials, but most of them only pointed out the problem without providing a solution. Even the tutorial mentioned above—although I haven’t seen it—I can roughly understand what it’s trying to say.

Due to confidentiality, I can only briefly describe the problem I encountered and how I solved it:

First, I had a normal map in SP and Unity that displayed correctly in the Mikk-T tangent space. However, it didn’t render correctly in Maya 2020.4 with Arnold 4 CPU—it showed artifacts like black edges, similar to what’s shown in this image.

This was caused by a low-poly model without UV splits and hard edges in areas with steep angles. You could fix it by adding geometry, redoing the UVs, and rebaking a nearly flat normal map (with very little color detail), following proper soft/hard edge guidelines.

However, there’s a simpler way to fix it:
In Substance, add your current normal map, then bake and export a world space normal map. In HyperShade, set the aiNormalMap node’s "Tangent map" attribute to False, and set your low-poly mesh to flat shading (all hard edges). This will cause the world space normals to override all existing normals. Note: there must be no weighted or smoothed normals.