Google is unable to sync iCal feed from Nextcloud

Steps to reproduce

1. Create a calendar in Nextcloud
2. Go to share options and copy the "Subscription link"
3. Add the calendar to Google Calendar
4. Wait for Google Calendar to sync
5. Add/edit an event in Nextcloud Calendar
6. Wait for Google Calendar to sync.

Expected behavior

Google Calendar should periodically update events from the ical feed. Maybe a few times per day. Google does correctly sync iCal feeds other than Nextcloud.

Actual behavior

Google Calendar does not ever refresh after the initial sync. Apparently this can be caused by missing fields: https://stackoverflow.com/questions/60560457/google-doesnt-sync-my-subscribed-ics-feed

Calendar app version

6.1.5

CalDAV-clients used

No response

Browser

No response

Client operating system

No response

Server operating system

No response

Web server

None

Database engine version

None

PHP engine version

None

Nextcloud version

32.0.5

Updated from an older installed version or fresh install

Updated from an older version

List of activated apps

Nextcloud configuration

Web server error log

Log file

Browser log

Additional info

No response

No source files or tests are identified in the issue. Start by reproducing the reported subscription flow and inspect the generated iCal feed against the linked missing-fields hypothesis; done means Google Calendar refreshes events after they change in Nextcloud.