This is certainly not coming from Cloudflare. The CF-Cache-Status: Dynamic says it was fetched from your origin.
Check with your hosting provider if they have any firewall or reverse proxy that could be generating this page. Your origin will only see Cloudflare IPs, and you must make sure that CF IPs are not being rate limited in any way.
Though this error is not appearing on your pages, the instructions on this link: 522 may help you find a solution.