As of 20 January 2022, sites that have their DNS A records pointing to 1.1.1.1 on Cloudflare will lead to a page that look something like this:
This error will appear even if you have a redirection rule in place.
The Cloudflare team has responded to this issue, and stated that the hostnames landing on an IP address will be validated to ensure they are linked to the same account in their systems, to prevent misconfiguration and potential abuse.
If you have been using 1.1.1.1 as a placeholder, you will have to change it to the reserved addresses 192.0.2.0 (IPv4) or 100:: (IPv6).
