Calendar export holds old data

Nextcloud version (eg, 19.0.4): 19.0.4
Operating system and version (eg, Ubuntu 20.04): Ubuntu 20.04
Apache or nginx version (eg, Apache 2.4.25): 2.4.29
PHP version (eg, 7.1): 7.2.24

The issue you are facing:

Currently we’re facing some problems with our calendar. A user used the CalDav-Synchronizer plugin for outlook which lead to some duplicated entries when we export/share (public share link) the calendar for a print-script.
Now, I had a look at the table oc_calendarobjects table in our database and found there duplicated entries with the same uid. I deleted the older entries, but when I download the ics-File via the export-link, the entry is still there.

So my question are:

  • How is the oc_calendarobjects-table related to the generated ics-File during export?
  • Where is this ics-File is generated?
  • Is there some kind of caching? If yes, can I rebuild it?