This issue has been added to the tracker:
https://winscp.net/tracker/1762

I am not parsing this log file.
The principal issue is that the time stamp is not logged correctly making it difficult to match the entries coming from the Session Debug Log with the corresponding XML Log entries. I am currently facing an issue whereby WinSCP cannot connect to a SFTP server while using a Private Key File and I need to use both logs to show where the issue most likely is.
Having CET + Day light saving time written as Zulu time and in the XML file the correct Zulu time might cause an needless off topic debate in that discussion about time stamps.
So, if it is not too much of an effort please, convert the Debug log time stamps to the correct Zulu time or leave the letter Z out in the Debug log time stamps.

OK, it seems that you are right.
But what issue do you have with that? Are you trying to parse the debug log? You should not. It's for debugging purposes only.

Hello,
I am running into a logging issue while automating using C#.
The issue is that the datetimestamp logged by the Session.DebugLogPath at DebugLogLevel 2 does not match the actual time while the logged XML fragment does.
The XML fragment shows the correct Zulu time but the Session.DebugLogPath write the CET + daylight saving time as Zulu time.

[2019-07-02 08:30:36.776Z] [0001] Read node 1: XmlDeclaration xml=version="1.0" encoding="UTF-8"
[2019-07-02 08:30:36.776Z] [0001] Log contents:
<?xml version="1.0" encoding="UTF-8"?>
<session xmlns="http://winscp.net/schema/session/1.0" name="userId@SomeServerAddress" start="2019-07-02T06:30:36.745Z">

Components used:
C#
.NET Framework 4.5.2
Windows 2008 R2
WinSCP.dll File Version 1.6.3.9407
WinSCP.exe 5.15.1.0 File Version 5.15.1.9407
Please see attached file.

Regards,
Arjan Douwes