The blog just leads to https://research.swtch.com/qr/draw/, which is the demo page of the blogs [1] and [2] written by Russ Cox many years ago about putting pictures in QR codes by manipulating the error correction codes in them
Hey thanks a lot, that should be the actual link behind the submission. Very interesting technique that boils down to encode a url with a ton of carefully shaped random numbers hidden in the fragment to generate the actual art.
Messing with that demo page, it seems to manipulate the URL you put in there too adding some numbers after an anchor tag (#) at the end, rather than just error correction.