your encryption mode is currently set to Full Strict
you do not have any page rules which lower that level
and your site is loading fine on HTTPS
then you have the guarantee that your site is properly and securely configured and that Cloudflare will validate your server certificate.
You have more details at Why you should choose Full Strict, and only Full Strict and let me congratulate you on your security awareness. Many people neglect that, even though setting up the certificate is a matter of seconds.
You might have a different certificate on your server. Just because there is no Origin certificate listed in your account does not mean there’s an issue.