i have tested the code now, you can use this regex
 
	 
 
            'cpanel_domain' => [
                'format' => [
                    'rule' => [[$this, 'validateHostName']],
                    'message' => Language::_('Cpanel.!error.cpanel_domain.format', true)
                ],
                'test' => [
                    'rule' => ['substr_compare', 'test', 0, 4, true],
                    'message' => Language::_('Cpanel.!error.cpanel_domain.test', true)
                ],
                'block' => [
                    // 'if_set' => true,
                    'rule' => ['matches', '/^((?!.ga|.tk|.td|.cf).)*$/'],
                    'message' => 'this domain is not alowded'
                ],
            ],