@BrokenEagle98 - I used the source field on the upload page, but it gave an error message for some reason...so as I'm the commissioner and have the original fullsized image, I just uploaded that instead.
(The source box keeps glitching out when I input addresses from Deviantart...?)
Just FYI, this isn't resized or upscaled - this is the original image file. The version I uploaded to Deviantart was a reduced/downscaled copy of this.
Then don't put DeviantArt as the main source. The comparison is done against the images that are found using the source link, which is why it's showing as upscaled.
You can link to it in a comment or in the Artist Commentary, but the source field should point to the actual image if possible. If it's just a file that you have, then leave the source blank. If the file is downloadable from elsewhere, then make that link the source.