Incorrect clock shown on login screen at first cold boot (Mac mini Apple Silicon)

Yes, this is a known and expected behaviour in Apple Silicon Macs

On Apple Silicon, the login window is displayed very early in the boot process, before the full network stack and NTP time synchronisation services are initialized. After a cold boot, macOS initially relies on the system's stored real-time clock value, which may be slightly out of sync. As a result, the clock shown on the login screen can be incorrect.

Once you log in, the user session starts, networking is fully initialized, and MacOS performs NTP. At that point, the system clock is corrected immediately and remains accurate. This is why the issue does not occur after restart, logout, sleep, or user switching.

This behavior is more noticeable on Apple Silicon systems and does not indicate a hardware fault, incorrect settings, or a configuration problem.

Mousjv wrote:

So there is no solution ?

One solution is, to just leave the Mac mini on and only allow the display(s) to turn off.

Have seen no reports of a bug in Mac OS that causes the time to be inaccurate on cold boot.

• Are you using a VPN or have any Antivirus software installed?

xtraxtraas wrote:

Yes, this is a known and expected behaviour in Apple Silicon Macs

I have not experienced that on either of my Silicon Macs or seen where that is expected behavior. Do you have any links that will provide this confirmation? Even without network access to request the time from the NTP server, my Macs still maintain accurate time through the internal clock.

FYI, for a few years now, the information on the login screen cannot be trusted. Even the Battery charge level is known to be incorrect. I suspect the more aggressive Privacy & Security within later version of macOS likely play a part in not being able to access up to date information (probably a bug & oversight due). At least that is when I first noticed the issue. In regards to the battery charge level shown on the login screen.....that appears to be more accurate than it was, but it still cannot be trusted.