AWS Certificate Manager - Generating Certificates for Subdomains Only

I am using CloudFlare to manage my domain, and with that, I have enabled SSL for this domain.

However, I created a subdomain with a CNAME record pointing to CloudFront, without cache, without any kind of SSL, without any kind of security for the subdomain.

In other words, CloudFlare is not hiding the real address of the CloudFront address.

When creating the digital certificate in AWS Certificate Manager for the subdomain, I do the validation using CNAME (without CloudFlare cache), however, there is an error in validation.

Does anyone know how to solve this?

Thank you!