I have to agree with @sjr that the errors you posted don’t aligin with your description of the issue or even the category here that you have posted in. In fact it is safe to say that your issue has nothing at all to do with Cloudflare, other than someone making an ill-informed decision to use the Cloudflare public DNS resolver on a mailserver that uses Spamhaus.
The error message you are seeing is commonly observed on improperly configured self-managed mail servers thay are using both the Spamhaus public DNS feeds and Cloudflare public DNS resolvers. Spamhaus doesn’t allow such use of their systems and will flag all queries that violate their terms.
You will need to reconfigure your mail server to no longer use open public resolvers, or disable its use of Spamhaus DNSbls if you cannot.