I should’ve mentioned I’m using a tablet. Although there’s a convoluted method involving long-hold and the Photos app, it still only save the low-res thumbnail.

Maybe try copy&pasting the URL instead of clicking it (so that no Referer is sent)?

Well, I'm not sure if there's a way of doing that on iOS, but I'm on desktop now anyway, so if anyone else just wants a direct link to the full-size image, here it is:

https://i.imgur.com/LdzBmpx.png

(edit: although, nope, even opening the direct URL to the image reroutes it to the low-res thumbnail version. I just don't think it's viewable on mobile — never mind!)

Note that this is the same URL that the one that was originally posted. :-/

Related HN discussion: https://news.ycombinator.com/item?id=21303283