Problem with One Calender gets displayed weird

[ScharadaValcta]

First I thought that its a fossify Calendar Issue

All Informations in
FossifyOrg/Calendar#957
If i should copy paste all infos here again just say it

[Honk2]

The provided ical file has two issues on each event.

1. Event duration is missing
   To make the events a full day event and thus be displayed in the top bar of your calendar app, each event should contain the line DURATION:P1D
2. The DTSTART tag should look like DTSTART;VALUE=DATE:20260116 but in your file it is DTSTART:20260116

You can test this with the modifies file attached.
The event on 20260113 is unmodified, the event on 20260114 has the DURATION tag added and the event on 20260116 has the DURATION added and the modified DTSTATtag.

abfalltermine.ics.txt

[ScharadaValcta]

If the ics File ist wrong.
Why is the Display of this Calendar in Thunderbird, Nextcloud Calendar and Google Calendar right?

[Honk2]

Looking at the standard, maybe there is an issue with icsx5.

According to section 3.8.2.4 the DTSTART is valid. And according to section 3.6.1 the duration "is taken to be one day." in this case (No end nor duration tag).

But I am not sure if the document above is the actual one or not.

[sunkup]

We are currently updating the synctools library used by ICSx⁵ which would be responsible here, but just got a major rewrite. The update in ICSx⁵ is tracked here. Once that issue is closed and released (I can't give a time estimate) there are high chances that the problem will be gone. So please wait for that. In case it does not fix the issue then, feel free to reply and mention me here and we will look into it again.