code: public function getForceLossyUrl()
      {
          $baseFile = $this->getBaseFile();
          $extension = pathinfo($baseFile, PATHINFO_EXTENSION); // @codingStandardsIgnoreLine
          $url = $this->getBaseFileUrl($baseFile);
          if ($extension == 'png' || $extension == 'bmp') {
              if ($this->isFastlyImageOptimizationEnabled() == false) {
                  $this->lossyUrl = $url . '?format=jpeg';
              } else {
                  $this->lossyParam = '&format=jpeg';
              }
          }
      }
docs: Creates a force lossy url param or url + param depending if IO is disabled or enabled