RDATE PERIOD with TZID doesn't seem to be recognised

[keunes]

Hello,

For the AntennaPod project we're dynamically generating an ics file based on the events created on our website (AntennaPod/antennapod.github.io#192). The ics file contains the following line:
RDATE;VALUE=PERIOD;TZID=Europe/Brussels:20221022T160000/20221022T170000.

When adding this to my Nextcloud calendar app as read-only calendar ('new subscription via link'), I get an error and the log shows this:

[webdav] Fout: Sabre\VObject\InvalidDataException: The supplied iCalendar datetime value is incorrect: 20221022T160000/20221022T170000 at <<closure>>

 0. /var/www/html/3rdparty/sabre/vobject/lib/DateTimeParser.php line 205
    Sabre\VObject\DateTimeParser::parseDateTime("20221022T160000/20221022T170000", DateTimeZone {})
 1. /var/www/html/3rdparty/sabre/vobject/lib/Recur/RDateIterator.php line 99
    Sabre\VObject\DateTimeParser::parse("20221022T160000/20221022T170000", DateTimeZone {})
 2. /var/www/html/3rdparty/sabre/vobject/lib/Recur/EventIterator.php line 362
    Sabre\VObject\Recur\RDateIterator->next()
 3. /var/www/html/3rdparty/sabre/vobject/lib/Recur/EventIterator.php line 335
    Sabre\VObject\Recur\EventIterator->next()
 4. /var/www/html/3rdparty/sabre/vobject/lib/Recur/EventIterator.php line 190
    Sabre\VObject\Recur\EventIterator->rewind()
 5. /var/www/html/apps/dav/lib/CalDAV/CalDavBackend.php line 2763
    Sabre\VObject\Recur\EventIterator->__construct([Sabre\VObject\C ... }])
 6. /var/www/html/apps/dav/lib/CalDAV/CalDavBackend.php line 1220
    OCA\DAV\CalDAV\CalDavBackend->getDenormalizedData("BEGIN:VCALENDAR ... n")
 7. /var/www/html/apps/dav/lib/CalDAV/WebcalCaching/RefreshWebcalService.php line 132
    OCA\DAV\CalDAV\CalDavBackend->createCalendarObject(4, "d1cdc89d-ca91-4 ... s", "BEGIN:VCALENDAR ... n", 1)

I'm wondering: why might this particular line throw an error? It seems to me based on the main error message that the VALUE=PERIOD (which is in the specs) might not be recognised. Would that be possible?

(Also reported here: nextcloud/server#44995)

Many thanks in advance. And apologies if I'm at the wrong address here.