Basic usage - canonical/snapd GitHub Wiki
Automatic refreshes
Installed snaps are automatically refreshed a few times a day, assuming a different revision is available on the channel being tracked.
More details about when it is to be triggered may be obtained via:
systemctl list-timers snapd.refresh.timer
Check whether the update worked with:
systemctl status -l snapd.refresh.service
and to view any output from the command run
sudo journalctl -u snapd.refresh.service