@Kahvro This is what bad_id is for. Don't just remove the source-link of images.
The source link was to a yande.re post of it. I didn't think yande.re counted as a valid source link. At least, not a good one. The thing is, this image USED to have a valid, non-yande.re source link. But it's deleted.
There, I changed the source link from the Yande.re link, to the actual Pixiv source, while also adding the bad pixiv id tag. Why this wasn't tagged with the pixiv link when itwas first uploaded, I don't know.
Any source is always better than none source. If the uploader uploaded the image from yandere, then this is the source that gets automatically added. It can also be the case, that the original image was already deleted on pixiv, but avaiable on yandere. In this case, I guess it's not incorrect to add the original source of the image, even though it's dead. But don't remove the source, just because it leads to a third-party site, if you don't also add the original source link.