To detect if the system has rebooted due to power fluctuation, added a script to log Pin, Pout status of PSUs every second. 
To detect if system has rebooted due to errors like watchdog reset or memory issues which don't generate core dump, few additional logs compared to syslog(/var/log/messages) might be present in journal. Also can view logs from different services.  Since journal isn't persisted, the journal logs are lost after reboot. Made changes to persist journal logs and added the previous kernel boot logs to snapshot.

Power supply info logged to:
cat /var/crash/power_info_2026-03-23.log | head -20

Mon Mar 23 21:57:55 IST 2026

PSU 1 Status     | 22h | ok  |  0.0 | Presence detected

PSU 1 Pin        | 28h | ok  |  3.0 | 64 Watts

PSU 1 Pout       | 27h | ok  |  3.0 | 56 Watts

PSU 2 Status     | 29h | ok  |  0.0 | Presence detected

PSU 2 Pin        | 2Fh | ok  |  3.0 | 68 Watts

PSU 2 Pout       | 2Eh | ok  |  3.0 | 56 Watts

Mon Mar 23 21:57:57 IST 2026

PSU 1 Status     | 22h | ok  |  0.0 | Presence detected

PSU 1 Pin        | 28h | ok  |  3.0 | 64 Watts

PSU 1 Pout       | 27h | ok  |  3.0 | 56 Watts

PSU 2 Status     | 29h | ok  |  0.0 | Presence detected

PSU 2 Pin        | 2Fh | ok  |  3.0 | 68 Watts

PSU 2 Pout       | 2Eh | ok  |  3.0 | 56 Watts
Previous boot logs seen with journalctl:
journalctl --list-boots

-1 9e78d2a9dcea44d38acda45714e4cd68 Tue 2026-03-24 16:37:49 IST—Tue 2026-03-24 16:44:48 IST

 0 9324002a929048d6904ed82fe5e19fa4 Tue 2026-03-24 16:45:38 IST—Tue 2026-03-24 17:22:11 IST
journalctl -b -1

-- Logs begin at Tue 2026-03-24 16:37:49 IST, end at Tue 2026-03-24 17:22:36 IST. --

Mar 24 16:37:49 AN kernel: pci 0000:b5:00.1: Signaling PME through PCIe PME interrupt

Mar 24 16:37:49 AN kernel: pcie_pme 0000:b2:02.0:pcie01: service driver pcie_pme loaded

Mar 24 16:37:49 AN kernel: ioapic: probe of 0000:00:05.4 failed with error -22

Mar 24 16:37:49 AN kernel: ioapic: probe of 0000:16:05.4 failed with error -22

Mar 24 16:37:49 AN kernel: ioapic: probe of 0000:64:05.4 failed with error -22

Mar 24 16:37:49 AN kernel: ioapic: probe of 0000:b2:05.4 failed with error -22