Fedora 33 released this fall plans to use systemd-resolved by default instead of nss-dns for domain name resolution. Systemd-resolved is used to provide domain name resolution services for DNS/DNSSEC/DNS-over-TLS/mDNS/LLMNR. It has been part of the systemd extension product for many years, but it is now disabled as a part of Fedora build by default status. In the Fedora 33 feature plan, glibc will perform name resolution using nss-resolve rather than nss-dns.
Ubuntu and some other Linux distributions already use systemd-resolved, but although Ubuntu has systemd-resolved enabled by default, it does not use nss-resolve. Instead, Ubuntu uses the traditional nss-dns provided upstream of glibc. Fedora’s approach is different from Ubuntu. Fedora hopes to follow all the systemd recommendations for performing domain name resolution, so it chose the upstream solution and used nss-resolve instead.
For more details about Fedora’s plan to use systemd-resolved from Fedora 33, please see this feature proposal.