There's a longstanding issue with using Cloudflare DNS. If you change Firefox's secure DNS provider settings to NextDNS the page loads without any captcha.
This is not the longstanding Cloudflare issue. That made Archive sties totally unreachable.
This Captcha issue occurs with non-cloudflare resolvers as well, although with great inconsistency. It depends on the resolver and the user's location when they query. Results can change hours later.