So, I am guessing that your router and cable modem are also plugged into the same UPS?
My hypothesis is that When the UPS was turned on, the Hubitat Hub started up quicker than your cable modem/router. Thus, when the Hubitat hub tried to update its time via NTP, it failed to access the internet, and thus its time was wrong. I believe the hub will eventually correct itself, however I am not sure how long this takes.
This is a well-known issue with the hub. Hopefully @gopher.ny will add this to the to-do list for a future update.
In the meantime, there is a community developed driver that can be used to uptime the hub’s time via NTP based on whatever logic you desire. Many use the hub’s system startup event in rule machine, to start a 10 minute delayed action to have the hub’s time updated.
