Events copied and pasted from another calendar displayed with wrong time

[logological]

I'm using DavMail 6.2.2 with Thunderbird 115 on openSUSE Tumbleweed. My system's timezone is set to America/Winnipeg (which is Central Time), and Thunderbird is configured to use this system timezone.

I'm subscribed to multiple remote calendars in Thunderbird, as well as one Exchange calendar exposed via a local DavMail server. If I copy an event from one of the remote calendars and paste it in the DavMail calendar, then its time gets shifted by one hour.

For example, in one of my remote calendars Thunderbird shows me an event that runs from 11:00 to 15:00 on 11 May 2024. I copy this event to the clipboard. The contents of the clipboard (when pasted to a text editor) are as follows:

BEGIN:VCALENDAR
PRODID:-//Mozilla.org/NONSGML Mozilla Calendar V1.1//EN
VERSION:2.0
BEGIN:VEVENT
DTSTAMP:20240424T142357Z
UID:aa8e43d5-a86e-481e-a2b0-c0f79d5432cd
SUMMARY:Science Rendezvous 
CATEGORIES:Computer Science
CATEGORIES: Microbiology
CATEGORIES: Chemistry
CATEGORIES: Biological Sciences
CATEGORIES: Mathematics
CATEGORIES: Physics and Astronomy
CATEGORIES: Statistics
CATEGORIES: Outreach
CATEGORIES: Biochemistry &amp\; Medical Genetics
DTSTART:20240511T160000Z
DTEND:20240511T200000Z
LOCATION:Fort Garry Campus
DESCRIPTION:Experience Canada's largest science and engineering festival fo
 r free at the UM Fort Garry campus! A fun-filled event with interactive boo
 ths\, activities and science shows for the young and the young at heart!\nV
 iew the full event details here: https://eventscalendar.umanitoba.ca/site/s
 cience/event/science-rendezvous-2/
CLASS:PUBLIC
BEGIN:VALARM
ACTION:DISPLAY
TRIGGER:-PT15M
DESCRIPTION:Science Rendezvous 
END:VALARM
END:VEVENT
END:VCALENDAR

If I then paste this event into my DavMail calendar on the same day, then it shows up as running from 12:00 until 16:00. The problem does not occur if I paste the event into a different remote calendar, such as the one running on my own self-hosted Radicale CalDAV server.

Perhaps this problem is related to Issue #342.