Ubuntu 25.10 is joining the likes of Red Hat Enterprise Linux and SUSE Linux Enterprise that are using Chrony as their Network Time Protocol (NTP) implementation. Ubuntu 25.10 is switching over to Chrony in enabling Network Time Security (NTS) support on Ubuntu Linux.
Ubuntu Linux is transitioning from systemd-timesync to Chrony with the Ubuntu 25.10 cycle in order to benefit from Network Time Security (NTS) support with this NTP client/server. The NTS standard is more secure than NTP and can prevent spoofing and avoid possible man-in-the-middle attacks.
Chrony can already be used on Ubuntu 25.04 if desired with having already made it into the main archive. Chrony is also already used in select Ubuntu Cloud images. Ubuntu 25.10 in early June is when the default changeover should take place for using Chrony by default.
More details on the Chrony plans for Ubuntu 25.10 via this Ubuntu mailing list post and the Launchpad bug tracker.