Cloudflare is one of the operators of egress nodes for iCloud Private Relay, along with Akamai and Fastly and maybe some others (IIRC). So you probably have issues with Archive.is when you're connected through Cloudflare. Although I'm not sure how DNS resolution works on private relay (since it's the DNS server rather than the egress proxy that causes the issue - but if the egress proxy is making the DNS requests then that would explain it).
I have the same issue and just now found it was because of Private Relay. I did not connect the fact that I had no issues accessing archive.is when I had a VPN on - which disables Private Relay. Since they got a location, not my location but a location they were hunky dory....
I saw this post and tried it with and without Private Relay and sure enough, turning it on is the issue. Good to know....
Edit: I updated Private Relay to "Maintain general location" for IP Address Location Settings and archive.is loads fine.
Second Edit: Maybe not, it all works now and I think it is either session or cache. I got to play around with it
Does enabling a VPN disable private relay or does it tunnel to the VPN through private relay? For some reason I have it in my head that it "double wraps" the traffic but I've never actually confirmed that for a fact.
