A post whose source is a direct link to a Weibo image, rather than to the Weibo post containing the image. These are considered bad links because there's no way to find the original Weibo post from the image link.
If you see this warning while uploading, it means you should paste the link to the Weibo post on the upload page, not the image itself. To do that on PC, copy the link from the date of the post and paste it into Danbooru's upload page.
