[Feature Request] Subscribe to calendars

I am not sure this is the place to report this (instead of nextcloud/server or nextcloud/tasks), but since the option to subscribe to a calendar is in the calendar app, I chose this repo.

Steps to reproduce

1. Create a new calendar in Nextcloud with task support
2. Copy the private link of the calendar
3. Add an event to the calendar
4. Add a task to the calendar
5. Add the calendar via + -> New subscription from link

I am using a Nextcloud calendar with task support but any endpoint with a calendar with tasks would work the same.

Expected behaviour

I would expect the tasks in the calendar to also appear in the Tasks app.

Actual behaviour

The calendar does not show in the tasks app.

Calendar app

2.3.4

CalDAV-clients used: None

Client configuration

Browser: Firefox Nightly 95.0a

Operating system: Macos

Server configuration

Operating system: Ubuntu 20.04.2 LTS

Web server: Apache

Database: MariaDB

PHP version: 8.0.3

Nextcloud Version: 22.2.3

Updated from an older installed version or fresh install: updated from 21

List of activated apps:

accessibility
comments
deck
files_external
files_versions
lookup_server_connector
password_policy
settings
text
user_ldap
activity
contacts
encryption
files_pdfviewer
files_videoplayer
news
photos
sharebymail
theming
user_status
admin_audit
contactsinteraction
extract
files_rightclick
firstrunwizard
nextcloud_announcements
privacy
support
twofactor_backupcodes
viewer
calendar
cookbook
federatedfilesharing
files_sharing
health
notes
provisioning_api
survey_client
twofactor_nextcloud_notification
weather_status
circles
dashboard
federation
files_texteditor
integration_google
notifications
recommendations
systemtags
twofactor_totp
workflowengine
cloud_federation_api
dav
files
files_trashbin
logreader
oauth2
serverinfo
tasks
updatenotification

Nextcloud configuration:

<?php
$CONFIG = array (
  'passwordsalt' => 'salt',
  'secret' => 'secret',
  'trusted_domains' =>
  array (
    0 => 'domain',
  ),
  'datadirectory' => '/var/www/html/nextcloud/data',
  'dbtype' => 'mysql',
  'version' => '22.2.3.0',
  'overwrite.cli.url' => 'url',
  'dbname' => 'dbname',
  'dbhost' => 'localhost',
  'dbport' => '3306',
  'dbtableprefix' => 'oc_',
  'mysql.utf8mb4' => true,
  'dbuser' => 'user',
  'dbpassword' => 'pass',
  'installed' => true,
  'htaccess.RewriteBase' => '/',
  'instanceid' => 'id',
  'theme' => '',
  'loglevel' => 0,
  'maintenance' => false,
  'overwrite' =>
  array (
    'cli' =>
    array (
      'url' => 'url',
    ),
  ),
  'htaccess' =>
  array (
    'RewriteBase' => '/',
  ),
  'updater.release.channel' => 'stable',
  'config_is_read_only' => true,
  'app_install_overwrite' =>
  array (
    0 => 'calendar',
  ),
  'twofactor_enforced' => 'true',
  'twofactor_enforced_groups' =>
  array (
    0 => 'admin',
  ),
  'twofactor_enforced_excluded_groups' =>
  array (
  ),
  'updater.secret' => 'secret',
);

Logs

Web server error log (e.g. /var/log/apache)

nothing relevant

Log file (data/nextcloud.log)

nothing relevant

Browser log

nothing relevant

Start by confirming whether this belongs in nextcloud/tasks, nextcloud/calendar, or nextcloud/server, then trace the “New subscription from link” flow described in the reproduction steps. The work is done when tasks from a subscribed calendar appear in the Tasks app, with behavior verified for a calendar endpoint that contains both events and tasks.