P: ArtBoard Containing Smart Object Export Problem and quality issue

I explored a little more and the problem seems to be related to the image scale itself and smart object transformation.
and the difference is that 
- export as : resize as smart objet THEN rasterize for output -> bad result
- save for the web : rasterize the smartobjet THEN resize -> good result

if you resize the smartoject you get the same bad result hence it's not artboard related 
let's close this one and reopen another ticket with smart object resizing problem

Here is an old post with the same problem i think : https://feedback.photoshop.com/photoshop_family/topics/photoshop_cc_pdf_smart_objects_still_render_b...

is it a linked or embedded smart object? how are you exporting? what file type are you exporting as? 

if you can provide all the details about your layers and process, then people here can try to reproduce and verify.