Blender 2.8 Evee - weird Shadow/Outline? On any other object shadows and outlines look soft and normal. Why is it that this object has these black outlines? And on the bottom there are white outlines.
You chose a wrong method to make sharp edges with the subdivision surface modifier. Don't make new edge loops near the geometry edge, use the edge creasing to earn it.
Increase the "Mean Crease" on the outer edges then dissolve the inner ones. Select them then hit "x" and select dissolve edges.