The parent appears to be a nearest-neighbor upscale (which looks like shit on non-pixel-art, to be frank); this version looks way better, even if it's smaller.
Maybe? Regardless, this isn't what the original artist uploaded, but I think I did figure out how original uploader got this so-called "sample".
If you open up the link without being logged into a pixiv account, you're only allowed to preview this image (should 403, since this is not intended for hotlinking) but basically it downscales the image to a maximum of 600x600 dimensions.
