Exception can't compare offset-naive and offset-aware datetimes

[Pka78]

I'm not quite sure if it's a bug of this addon, but I can't think of any other place where I can go to unpack this. After I added the children's school timetable through the addon, the log shows:

The addon does not add Events to the calendar. The addon throws the following errors:
2023-10-27 10:53:19.940 ERROR (MainThread) [custom_components.ical] Exception can't compare offset-naive and offset-aware datetimes in starts/ends: SUK.3 (TuoMa) (YMA 3008) - Start: 2023-09-29 12:15:00+03:00 - End: 2023-09-29 13:00:00+03:00, RRule: vRecur({'FREQ': ['WEEKLY'], 'UNTIL': [datetime.datetime(2023, 12, 22, 13, 0, tzinfo=tzfile('/usr/share/zoneinfo/UTC'))]})

With Curl i get, when i read the ics address:
UID:www.starsoft.fi/YMA lv 23-24/9D YMA students name/1112
DTSTAMP:20231027T131500
DTSTART;TZID=Europe/Helsinki:20231027T131500
DTEND;TZID=Europe/Helsinki:20231027T140000
RRULE:FREQ=WEEKLY;UNTIL=20231110T140000
SUMMARY:UEEV.4 (KauAn) (YMA 2101)
DESCRIPTION:YMA 2101 2101\nKauAn Kaukonen Anette\n9D YMA
CATEGORIES:Education
LOCATION:YMA 2101 2101
RESOURCES:KauAn,YMA 2101
END:VEVENT
BEGIN:VEVENT

Is it this addon, or could please somebody point me to right direction.