Deck event treated as "task" and not "event". Will not integrate with DAV calendar

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Describe the bug
When I add an item that is calendar driven, it is integrating it as a 'task' and not as an 'event'. Therefore other software that link to it (in this case Thunderbird) are not displaying it as a calendar item. How to modify this behavior so it is treated like a native calendar event.

Is this a bug / built in hardwire or is this changeable somewhere? Cannot find it.

Screenshots
Created a short video to better highlight the issue:

• https://www.youtube.com/watch?v=AQs5R2J6154

Operating system: Ubuntu 20.04

Web server: Linux

Database: Mysql

PHP version: 7.2

Nextcloud version: (see Nextcloud admin page) 20

Where did you install Nextcloud from: Source

Signing status:

Login as admin user into your Nextcloud and access
http://example.com/index.php/settings/integrity/failed
paste the results here.

No errors have been found.

List of activated apps:

Accessibility
Calendar Collaborative tags Comments Community Document Server Contacts Interaction Custom CSS Dashboard Deck Deleted files Federation  File sharing First run wizard Group folders LDAP user and group backend Log Reader Monitoring Nextcloud announcements Notifications Notifications for calendar event updates ONLYOFFICE Password policy PDF viewer Photos Privacy Recommendations Right click Share by mail Support Text Theming Update notification Usage survey User status Versions Video player Weather status 

If you have access to your command line run e.g.:
sudo -u www-data php occ app:list
from within your Nextcloud installation folder

Nextcloud configuration:

If you have access to your command line run e.g.:
sudo -u www-data php occ config:list system
from within your Nextcloud installation folder

or

Insert your config.php content here
Make sure to remove all sensitive content such as passwords. (e.g. database password, passwordsalt, secret, smtp password, …)

{
    "system": {
        "instanceid": "***REMOVED SENSITIVE VALUE***",
        "passwordsalt": "***REMOVED SENSITIVE VALUE***",
        "secret": "***REMOVED SENSITIVE VALUE***",
        "trusted_domains": [
            "cloud.compumatter.biz"
        ],
        "datadirectory": "***REMOVED SENSITIVE VALUE***",
        "dbtype": "mysql",
        "version": "20.0.6.1",
        "overwrite.cli.url": "https:\/\/cloud.compumatter.biz",
        "dbname": "***REMOVED SENSITIVE VALUE***",
        "dbhost": "***REMOVED SENSITIVE VALUE***",
        "dbport": "",
        "dbtableprefix": "oc_",
        "mysql.utf8mb4": true,
        "dbuser": "***REMOVED SENSITIVE VALUE***",
        "dbpassword": "***REMOVED SENSITIVE VALUE***",
        "installed": true,
        "onlyoffice": {
            "verify_peer_off": true
        },
        "maintenance": false,
        "theme": "",
        "loglevel": 2,
        "ldapIgnoreNamingRules": false,
        "ldapProviderFactory": "OCA\\User_LDAP\\LDAPProviderFactory",
        "mail_smtpmode": "smtp",
        "mail_smtpsecure": "tls",
        "mail_sendmailmode": "smtp",
        "mail_from_address": "***REMOVED SENSITIVE VALUE***",
        "mail_domain": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpauthtype": "LOGIN",
        "mail_smtpauth": 1,
        "mail_smtphost": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpport": "587",
        "mail_smtpname": "***REMOVED SENSITIVE VALUE***",
        "mail_smtppassword": "***REMOVED SENSITIVE VALUE***"
    }
}

Are you using an external user-backend, if yes which one: LDAP/ActiveDirectory/Webdav/...
LDAP

Start by tracing Deck's calendar-driven item integration and the DAV export path, then reproduce the result in Thunderbird using the issue's Ubuntu, Nextcloud 20, and MySQL setup. Determine where the item type is assigned and verify completion by confirming that the exported item is recognized as a calendar event rather than a task.