According to SauceNao the original source for this is https://deviantart.com/view/70903508 but it's deleted and was not archived on the Wayback Machine. Was at least able to get the artist's handle from the reverse search result.
Based on a google translation of the commentary, it's a younger Vim Jeturk with a speculative take on what Guel's mother (who's never shown or mentioned in the show) could look like.
Love the rough hands; you never get to see that on female characters! Wondering if anyone could share more examples if there are any out there, but I doubt it...
I'm posting this as an image sample because removing all of the image sample parameters (c_limit,fl_lossy,h_9000,w_1920,f_auto,q_auto) from the URL at once gives me an error page. I did some testing, and if I leave one parameter in the URL, I don't get an error page. c_limit affects the image the least, so I left that in. If the uncompressed image becomes available, please replace this post, as well as any others from this artist that are tagged with image_sample.
Some monitors' colors go wonky if you stand them on the side or flip them. And no, I didn't try it with a computer screen, I had to stand a regular monitor on its side because my old passport photo system displayed the pictures rotated, because it was retarded...
I've turned my laptop and my LCD both on their sides, though the LCD needs supports. It's never been for the purpose in the picture though, always for looking at tall pictures on what is a wide screen; They fit infinitely better that way.
the artist is doyeoun, who may be the same person as 6_(yuchae), but other than them being tagged as the artist here i can't find anything indicating 6 is the artist, as it has no source. is there any proof of them drawing this?