https://letsencrypt.org/docs/certificate-compatibility/ does not list Fedora as being known compatible. However, as far as I can tell, the ca-certificates package has the Let's Encrypt root certificate (using lynx on https://helloworld.letsencrypt.org/ works just fine, lsof shows lynx doesn't use NSS to get certificates, and strace shows that lynx opens /etc/pki/tls/cert.pem)
Sorry if this isn't the right place to report the issue.
Not a bug in a Fedora package.
I suggest you send email to the maintainer of that web page.
This web page doesn't even talk about the Let's Encrypt root, but about the earlier requirement of trusting a specific IdenTrust root.
All currently supported versions of Fedora should be fully compatible.