What happened to auto restart on the Mac?

It went away with Ventura. You can still use auto startup and shutdown but requires you use Terminal to make the script.

Using Terminal to set start up and shut down each day

Separately:

Shut down each day at 9:30 pm:

Sudo pmset repeat shutdown MTWRFSU 21:30:00  and hit return

Enter PW if required

Startup every day at 6:00AM:

Sudo pmset repeat wake MTWRFSU 6:00:00 and hit return

To have both startup and shutdown:

Sudo pmset repeat poweron MTWRFSU 6:00:00 shutdown MTWRFSU 21:30:00

To check if these were set:

Pmset -g sched

To cancel all settings:

Sudo pmset repeat cancel and hit return

Monday=M

Tuesday=T

Wednesday=W

Thursday=R

Friday=F

Saturday=S

Sunday=U

The ability to automatically start up and shut down a Mac at specified times has not been removed. You just need a Terminal script as tbirdvet wrote. It is described in Schedule your Mac to turn on or off in Terminal - Apple Support.

Why did auto restart go away?

Apple has never used the terminology "auto restart" for any Mac feature. If you want a Mac to start up automatically after a power failure, that feature is described in Change Energy Saver settings on a Mac desktop computer - Apple Support. As an IT support person, you should know using correct terminology helps promote effective communication.

I believe we are talking about two different functions. The one I reference use to be in the Energy Saver pane to auto start and/or auto shutdown at a specific time. Please clarify your issue.

I have also asked Apple why that user interface function was removed. You can send your question or feedback at this link:

Feedback - macOS - Apple