Wrong time zone information for Europe/Istanbul
I've just realize that the pfsense's time information is not correct.
In my case, the time zone has been set to Europe/Istanbul for months and it was correct in the past. However, it is now 2 hours behind the actual time.
Since Istanbul is on the both continents (Europe and Asia), I set the time zone to Asia/Istanbul (UTC+02:00), and everything works fine.
We get that info from the master TZ database, it's not ours. So if it's incorrect, it's incorrect higher up than we can control.
The TZ databases were just updated a month or two ago on 2.1 and 2.0.x, so it's possible that they relocated the definition or deprecated the Europe version.