Odd problem.
In Terminal I do a "Last Reboot" command and instead of getting a "Reboot" line with a date and time, I get "wtmp begins Mon Jun 20 18:18" Which date time is when I asked for the last reboot not when the reboot occurred. Works OK on my MBP.
This on a Mac Mini 2018.
TIA
Mac mini, macOS 12.4