Hi Pascal,
Can you give us some more information, plaese?
Like did you model this in Blender and the Exported it to Marmoset for Baking?
If so, did you try Baking the Normals in Blender, to see if you get the same problem?
My guess is, that it’s either something in the Model, or something with the Exporting, but it could of course be something else.
