code: public function recordIsPublished()
      {
          if (!$this->owner->record->checkVersioned()) {
              return false;
          }
  
          if (!$this->owner->record->isInDB()) {
              return false;
          }
  
          $baseClass = DataObject::getSchema()->baseDataClass($this->owner->record);
          $stageTable = DataObject::getSchema()->tableName($baseClass) . '_Live';
  
          return (bool) DB::query("SELECT \"ID\" FROM \"{$stageTable}\" WHERE \"ID\" = {$this->owner->record->ID}")
              ->value();
      }
docs: Determines if the current record is published
  @return boolean