Objects shading breaks if duplicated in wireframe mode(must have a normal map node)
Add a material to an object, set shader to 'Principled BSDF', Set normal to 'Normal Map', press shift+z, select object, alt+d to duplicate, press shift+z. the object should now be black. To fix, switch shading mode in the top right and then switch back to eevee.
You don't need to actually use a normal map, just setting up the material like so suffices.