diff --git a/core/modules/big_pipe/src/Render/BigPipeResponse.php b/core/modules/big_pipe/src/Render/BigPipeResponse.php
index 18df40409f..da0430298a 100644
--- a/core/modules/big_pipe/src/Render/BigPipeResponse.php
+++ b/core/modules/big_pipe/src/Render/BigPipeResponse.php
@@ -97,6 +97,7 @@ protected function populateBasedOnOriginalHtmlResponse() {
     // We don't want an 'Content-Length' header added by
     // \Symfony\Component\HttpFoundation\Response::send, so we add an empty
     // 'Transfer-Encoding' header to prevent that.
+    // @todo: revisit pending https://github.com/symfony/symfony/issues/46449
     $this->headers->set('Transfer-Encoding', '');
   }