Fazendo append da extensão do formato ao filename.

src/app/Services/JasperServerRequestService.php

@@ -261,9 +261,11 @@ class JasperServerRequestService implements JasperServerRequestServiceContract
     private function setHeader(string $report, ?string $filename = null)
     {
         if (!$filename) {
-            $filename = uniqid() . '.' . $this->format;
+            $filename = uniqid();
         }
 
+        $filename = $this->appendFormatExtension($filename);
+
         header('Cache-Control: must-revalidate');
         header('Pragma: public');
         header('Content-Description: File Transfer');
@@ -272,4 +274,13 @@ class JasperServerRequestService implements JasperServerRequestServiceContract
         header('Content-Length: ' . strlen($report));
         header('Content-Type: ' . ReportFormatEnum::getMimeType($this->format));
     }
+
+    /**
+     * @param string $filename
+     * @return string
+     */
+        private function appendFormatExtension(string $filename): string
+    {
+        return $filename . '.' . $this->format;
+    }
 }