I assumed it was the result of the "bubbling" that they describe in the video that also accounts for the grainy appearance of the surface; presumably the bubbling would be visible like this side on?
One idea is to embed the guesses in the url fragment (perhaps delta encoded) and from that url fragment, generate a social media preview image with a horizontal discrete gradient of the guesses.
You would need a server to generate the preview images ofc, but something like a subdomain redirect to a cloudflare worker or what-have-you could be sufficient. If done right the generated previews could be pretty small.
> How's things? > Not bad.