There are currently 2 similar named sites added to Cloudflare. For example, abc.com (1) and theabc.com (2). The latter is the primary domain.
When adding a page rule for to permanently (1) redirect to (2), it returns the error message “Forwarding URL matches the target and would cause a redirect loop”.
The rule is https://*abc.com/*. The preceding asterisk matches “the”. Adding a dot/period after * e.g. *.abc resolves the error. This however does not redirect https://abc.com to (2) with a subdomain of www.