What were you trying to do that didn't work?

After change the RTC time in the RHEL 9 guest, and disable the NTP time, does the  guest  Universal time and Local time would be changed to build time for systemd?

Is this by design?  Are there any special reason? When was this feature introduced? Is it from systemd version 246? As RHEL 8 change all time to RTC time

could you help explain where set these time?

Please provide the package NVR for which bug is seen:

systemd-252-33.el9.x86_64

How reproducible:

100%

Steps to reproduce

1. Disable the NTP and System clock synchronized
2. Add rtc.starttime = " 1546300800" (2019-01-01 12:00:00 AM) to rhel vmx file, then power on the VM
3. Check the guest time with #timedatectl
4. Also check the systemd info with #rpm -qi systemd

Expected results

The guest time keep with the RTC time

Actual results

the guest time will be changed to the systemd build time 

[root@vm-197-23 ~]# timedatectl 
               Local time: Fri 2024-04-26 08:02:19 CST
           Universal time: Fri 2024-04-26 00:02:19 UTC
                 RTC time: Tue 2019-01-01 00:04:21
                Time zone: Asia/Shanghai (CST, +0800)
System clock synchronized: no
              NTP service: inactive
          RTC in local TZ: no

Additional Info:

On RHEL 8.9, the guest time is changed to "2019-01-01 00:00:00".

[root@vm-198-138 ~]# timedatectl 
               Local time: Tue 2019-01-01 08:12:54 CST
           Universal time: Tue 2019-01-01 00:12:54 UTC
                 RTC time: Tue 2019-01-01 00:12:54
                Time zone: Asia/Shanghai (CST, +0800)
System clock synchronized: no
              NTP service: inactive
          RTC in local TZ: no
[root@vm-198-138 ~]# cat /etc/redhat-release 
Red Hat Enterprise Linux release 8.10 (Ootpa)