Merging verts by distance breaks smooth shading (Blender 2.8) I created a wall piece from a cube, applied smooth shading to it and then used the array modifier, but after merging the verts by distance, it mixes up the normals in a random fashion, while for the simple, unmodified sphere there are no issues.
Assuming your weld (or merge by distance) is setup correctly, just define a sharp edge and then add an auto smooth