diff --git a/tools/internal_ci/windows/grpc_run_tests_matrix.bat b/tools/internal_ci/windows/grpc_run_tests_matrix.bat
index 07a7c74b9d3..cd410a51ef3 100644
--- a/tools/internal_ci/windows/grpc_run_tests_matrix.bat
+++ b/tools/internal_ci/windows/grpc_run_tests_matrix.bat
@@ -20,6 +20,9 @@ If Not "%RUN_TESTS_FLAGS%"=="%RUN_TESTS_FLAGS:python=%" (
 )
 call tools/internal_ci/helper_scripts/prepare_build_windows.bat || exit /b 1
 
+@rem TODO(https://github.com/grpc/grpc/issues/28011): Remove once Windows Kokoro workers'
+@rem   Python installs have been upgraded. Currently, removing this line will cause
+@rem   run_tests.py to fail to spawn test subprocesses.
 python3 tools/run_tests/start_port_server.py
 
 python3 tools/run_tests/run_tests_matrix.py %RUN_TESTS_FLAGS%