Subscription Calendar added via iOS not working

Steps to reproduce

1. Open Calendar App on iOS
2. "Add Calendar" -> "Add Subscription Calendar"
3. enter ics link (e.g. webcal://i.cal.to/ical/2701/bundesliga/fc-bayern-muenchen/6c0af04a.d0540e04-4c41d215.ics)
4. choose to add calendar to Nextcloud account
5. subscribed calendar works fine on iOS
6. subscribed calendar is listed on Nextcloud, but no events are loaded

Expected behavior

The subscribed calendar events should show in Nextcloud Calendar App.

Actual behaviour

No events are shown from subscribed calendar.

Calendar app version

5.0.0.

CalDAV-clients used

iOS Calendar

Browser

Firefox 131.0.2

Client operating system

Windows

Server operating system

Debain 12

Web server

Nginx

Database engine version

MariaDB

PHP engine version

PHP 8.2

Nextcloud version

30.0.0

Updated from an older installed version or fresh install

Fresh install

List of activated apps

Enabled:

• activity: 3.0.0
• bookmarks: 15.0.2
• bruteforcesettings: 3.0.0
• calendar: 5.0.0
• circles: 30.0.0-dev
• cloud_federation_api: 1.13.0
• comments: 1.20.1
• contacts: 6.1.0
• contactsinteraction: 1.11.0
• dashboard: 7.10.0
• dav: 1.31.1
• deck: 1.14.1
• federatedfilesharing: 1.20.0
• federation: 1.20.0
• files: 2.2.0
• files_downloadlimit: 3.0.0
• files_external: 1.22.0
• files_pdfviewer: 3.0.0
• files_reminders: 1.3.0
• files_sharing: 1.22.0
• files_trashbin: 1.20.1
• files_versions: 1.23.0
• firstrunwizard: 3.0.0
• forms: 4.3.1
• logreader: 3.0.0
• lookup_server_connector: 1.18.0
• mail: 4.0.1
• memories: 7.4.1
• nextcloud_announcements: 2.0.0
• notes: 4.11.0
• notifications: 3.0.0
• oauth2: 1.18.1
• password_policy: 2.0.0
• photos: 3.0.2
• previewgenerator: 5.6.0
• privacy: 2.0.0
• provisioning_api: 1.20.0
• recognize: 8.1.1
• recommendations: 3.0.0
• related_resources: 1.5.0
• serverinfo: 2.0.0
• settings: 1.13.0
• sharebymail: 1.20.0
• spreed: 20.0.1
• support: 2.0.0
• survey_client: 2.0.0
• systemtags: 1.20.0
• tasks: 0.16.1
• text: 4.1.0
• theming: 2.5.0
• twofactor_backupcodes: 1.19.0
• updatenotification: 1.20.0
• user_status: 1.10.0
• viewer: 3.0.0
• weather_status: 1.10.0
• webhook_listeners: 1.1.0-dev
• whiteboard: 1.0.3
• workflowengine: 2.12.0
  Disabled:
• admin_audit: 1.20.0
• drawio: 3.0.3 (installed 3.0.3)
• encryption: 2.18.0
• integration_github: 3.0.0 (installed 3.0.0)
• integration_homeassistant: 0.0.5 (installed 0.0.5)
• richdocuments: 8.5.1 (installed 8.5.1)
• richdocumentscode: 24.4.802 (installed 24.4.802)
• suspicious_login: 8.0.0
• twofactor_nextcloud_notification: 4.0.0
• twofactor_totp: 12.0.0-dev
• user_ldap: 1.21.0

Nextcloud configuration

No response

Web server error log

No response

Log file

No response

Browser log

No response

Additional info

No response

Start by reproducing the reported flow with the supplied webcal:// subscription URL: add it through iOS Calendar to a Nextcloud account, then inspect the subscribed calendar and relevant server responses. The work is done when events from an iOS-added subscription calendar are loaded and displayed in Nextcloud Calendar; no source files or tests are identified in the report.