There are only two ways of realistically demonstrating encoding artifacts: decode the actual format client side or transmit a lossless encoding. GIF surely isn't lossless, but its losses are somewhat orthogonal to those of the encodings in question. Still, yet could have done with much less of the same.

I think their blogs are still based off Blogger which hasn't been updated in quite some time. (which they own so they could fix themsleves..)

If it's stupid but it works, it's still stupid.

But it works.

If it's clever and it doesn't work, it's surely clever ... but it doesn't work

It has been known and well understood for many years now that you should use video (like mp4 or webm) in place of gifs if you want to save bandwidth.

would encoding your AV1 encoding demo with another encode produce the desired effects?