Event email reminders are sent only to sharers with edit rights

Steps to reproduce

1. Create a personal calendar and share with individuals. Give calendar edit rights only to some of them.
2. Setup an event with an email alert
3. Wait for the reminder to be sent

Expected behavior

Every individual with calendar access should receive the email alert.

Actual behaviour

Only those with edit rights actually receive the email notification.

Calendar app version

3.0.6

CalDAV-clients used

No response

Browser

No response

Client operating system

No response

Server operating system

nextcloud:23.0.1-apache docker image on Ubuntu 20.04 host

Web server

Apache

Database engine version

MariaDB

PHP engine version

PHP 8.0

Nextcloud version

23.0.1

Updated from an older installed version or fresh install

Updated from an older version

List of activated apps

Enabled:
  - calendar: 3.0.6
  - circles: 23.0.1
  - cloud_federation_api: 1.6.0
  - dav: 1.21.0
  - federatedfilesharing: 1.13.0
  - files: 1.18.0
  - lookup_server_connector: 1.11.0
  - oauth2: 1.11.0
  - provisioning_api: 1.13.0
  - settings: 1.5.0
  - sociallogin: 4.11.0
  - theming: 1.14.0
  - twofactor_backupcodes: 1.12.0
  - viewer: 1.7.0
  - workflowengine: 2.5.0
Disabled:
  - accessibility: 1.7.0
  - activity: 2.14.3
  - admin_audit
  - comments: 1.11.0
  - contactsinteraction: 1.2.0
  - dashboard: 7.1.0
  - encryption
  - federation: 1.11.0
  - files_external
  - files_pdfviewer: 2.1.0
  - files_rightclick: 1.0.0
  - files_sharing: 1.14.0
  - files_trashbin: 1.11.0
  - files_versions: 1.15.0
  - files_videoplayer: 1.10.0
  - firstrunwizard: 2.10.0
  - logreader: 2.6.0
  - nextcloud_announcements: 1.10.0
  - notifications: 2.9.0
  - password_policy: 1.11.0
  - photos: 1.3.0
  - privacy: 1.5.0
  - recommendations: 1.0.0
  - serverinfo: 1.11.0
  - sharebymail: 1.11.0
  - support: 1.4.0
  - survey_client: 1.9.0
  - systemtags: 1.11.0
  - text: 3.2.0
  - updatenotification: 1.11.0
  - user_ldap
  - user_status: 1.1.1
  - weather_status: 1.1.0

Nextcloud configuration

{
    "system": {
        "htaccess.RewriteBase": "\/",
        "memcache.local": "\\OC\\Memcache\\APCu",
        "apps_paths": [
            {
                "path": "\/var\/www\/html\/apps",
                "url": "\/apps",
                "writable": false
            },
            {
                "path": "\/var\/www\/html\/custom_apps",
                "url": "\/custom_apps",
                "writable": true
            }
        ],
        "passwordsalt": "***REMOVED SENSITIVE VALUE***",
        "secret": "***REMOVED SENSITIVE VALUE***",
        "trusted_domains": [
            "localhost",
            "calendar.herd.cloud.infn.it"
        ],
        "datadirectory": "***REMOVED SENSITIVE VALUE***",
        "dbtype": "mysql",
        "version": "23.0.1.2",
        "overwrite.cli.url": "http:\/\/localhost",
        "dbname": "***REMOVED SENSITIVE VALUE***",
        "dbhost": "***REMOVED SENSITIVE VALUE***",
        "dbport": "",
        "dbtableprefix": "oc_",
        "mysql.utf8mb4": true,
        "dbuser": "***REMOVED SENSITIVE VALUE***",
        "dbpassword": "***REMOVED SENSITIVE VALUE***",
        "installed": true,
        "instanceid": "***REMOVED SENSITIVE VALUE***",
        "maintenance": false,
        "skeletondirectory": "\/var\/www\/html\/core\/empty-skeleton",
        "defaultapp": "calendar",
        "overwriteprotocol": "https",
        "mail_smtpmode": "smtp",
        "mail_smtpauthtype": "LOGIN",
        "mail_sendmailmode": "smtp",
        "mail_smtpauth": 1,
        "mail_smtpsecure": "tls",
        "mail_smtphost": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpport": "587",
        "mail_from_address": "***REMOVED SENSITIVE VALUE***",
        "mail_domain": "***REMOVED SENSITIVE VALUE***",
        "loglevel": 2,
        "mail_smtpname": "***REMOVED SENSITIVE VALUE***",
        "mail_smtppassword": "***REMOVED SENSITIVE VALUE***"
    }
}

Web server error log

No response

Log file

No response

Browser log

No response

Additional info

I asked also on NextCloud forum but I got no response so I guess it might be a real bug rather than a simple misconfiguration.

Reproduce the reminder flow from the issue using a shared personal calendar with separate read and edit permissions on Nextcloud 23.0.1 and Calendar 3.0.6. Trace how event email recipients are selected, then add coverage showing that all calendar users receive alerts regardless of edit rights.