https://observatory.mozilla.org/analyze/papajohns.com.ec#tls distinguishes the Let’s Encrypt SSL used by Cloudflare as an untrusted or invalid certificate. However, this is not entirely true, you can check that Cloudflare SSL is valid using https://decoder.link/sslchecker
and the Name cheap SSL on the server also is working https://decoder.link/sslchecker/papajohns.com.ec/443
and Full (strict) SSL mode is enabled
But Mozilla and Burp identified the certificate as not trusted
The Mozilla observatory is referring to a certificate that’s just expired (6am UTC today), however the site itself is currently using a new certificate issued an hour before. It seems the certificate has just updated and the Mozilla observatory has cached and is reporting on the old one.