Steps to reproduce the issue

Create a simple component with an install script containing a function to addEmailTemplate for this 3rd party component.
`

       /**
	 * Create a new Mail Template
	 */
	public function addMailTemplate($template_id)
	{
        $result = MailTemplate::createTemplate(
        	'com_'.$this->compName.'.'.$template_id,
        	'COM_'.STRTOUPPER($this->compName).'_EMAILTMPL_'.STRTOUPPER($template_id).'_SUBJECT',
        	'COM_'.STRTOUPPER($this->compName).'_EMAILTMPL_'.STRTOUPPER($template_id).'_BODY',
        	array("name","sitename","link_text")
        );

		Factory::getApplication()->enqueueMessage('Email Template Record Created . . . ');

	}

`

Expected result

A new record to be created in the database with all the relevant data elements.

Actual result

Missing extension data element and the tags are double arrayed (if that's a thing). So the record doesn't appear in the template listing in the backend. After manually inserting the extension element, trying to open the record from the admin list to edit, fails due to the tags array is within a blank array.

System information (as much as possible)

PHP 8.1
Joomla 4.2.6
MySQL 8.0.27

Additional comments

If I update the createTemplate function in MailTemplate to the following all works as expected.
`

    /**
     * Insert a new mail template into the system
     *
     * @param   string  $key       Mail template key
     * @param   string  $extension Extension
     * @param   string  $subject   A default subject (normally a translatable string)
     * @param   string  $body      A default body (normally a translatable string)
     * @param   array   $tags      Associative array of tags to replace
     * @param   string  $htmlbody  A default htmlbody (normally a translatable string)
     *
     * @return  boolean  True on success, false on failure
     *
     * @since   4.0.0
     */
    public static function createTemplate($key, $extension, $subject, $body, $tags, $htmlbody = '')
    {
        $db = Factory::getDbo();

        $template = new \stdClass();
        $template->template_id = $key;
        $template->extension = $extension;
        $template->language = '';
        $template->subject = $subject;
        $template->body = $body;
        $template->htmlbody = $htmlbody;
        $template->attachments = '';
        $params = new \stdClass();
        $params->tags = $tags;
        $template->params = json_encode($params);

        return $db->insertObject('#__mail_templates', $template);
    }

`