At the time of this comment, this post was the artist's pixiv banner and available at https://i.pximg.net/background/img/2021/07/11/01/18/51/32499085_60236a1a59838209b7cf3afc8342c636.jpg but that doesn't seem linkable to the artist so I used their main pixiv page as the source. Don't know if there's a better way to source it.