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'
],
],