The notifications are coming from a background update called “macOSInstallerNotification_RC” that was pushed to all Ventura users at a random time on Jan 10, but I’m skeptical of the reports that it forces a Sonoma update without the users permission. If the computer is shutdown at that random time, it will simply be delayed another 24 hours. I’m not sure at what point the notification is then displayed after installation. It’s unlikely that any FB will be acted upon since it’s behaving as it was designed to.
This isn’t the first time Apple has done this.