I have a website that uses .media and your service says it’s not a valid domain? It’s 2020… really?
If you only provide .com then that would be good to know.
What’s the actual domain you’re trying to add?
.media tld with Cloudflare Registrar, https://www.cloudflare.com/tld-policies/. That would not be possible if the domains were not first active on cloudflare.
Edit - Just tried to add the zone without an issue, suspect you hit a temporary glitch.