It’s very strange. I went down this rabbit hole a few months ago and this HN comment (https://news.ycombinator.com/item?id=19828702) was the best summary I could find of the situation.
TLDR: archive.is doesn’t play nice with its DNS results and Cloudflare refuses to fix it on their end.
TLDR: archive.is doesn’t play nice with its DNS results and Cloudflare refuses to fix it on their end.