Fedora 33 is the first Fedora release to support NTS. NTS is a new authentication mechanism for NTP. It enables clients to verify that the packets they receive from the server have not been modified while in transit. The only thing an attacker can do when NTS is enabled is drop or delay packets. See RFC8915 for further details about NTS.

https://fedoramagazine.org/secure-ntp-with-nts/ https://tools.ietf.org/html/rfc8915