diff --git a/docs/changelog.rst b/docs/changelog.rst
index ab2e062b..0a6304ae 100644
--- a/docs/changelog.rst
+++ b/docs/changelog.rst
@@ -53,11 +53,15 @@ Bugfixes
 
 - Use ``email.message`` instead of ``cgi`` as ``cgi`` has been deprecated (`#969 <https://github.com/pypa/twine/issues/969>`_)
 
+Features
+^^^^^^^^
+
+- Remove support for usernames other than ``__token__`` when uploading to PyPI and TestPyPI (`#1040 <https://github.com/pypa/twine/issues/1040>`_)
 
 Misc
 ^^^^
 
-- `#931 <https://github.com/pypa/twine/issues/931>`_, `#991 <https://github.com/pypa/twine/issues/991>`_, `#1028 <https://github.com/pypa/twine/issues/1028>`_, `#1040 <https://github.com/pypa/twine/issues/1040>`_
+- `#931 <https://github.com/pypa/twine/issues/931>`_, `#991 <https://github.com/pypa/twine/issues/991>`_, `#1028 <https://github.com/pypa/twine/issues/1028>`_
 
 
 Twine 4.0.2 (2022-11-30)
diff --git a/twine/settings.py b/twine/settings.py
index dc73adce..9f3aefb1 100644
--- a/twine/settings.py
+++ b/twine/settings.py
@@ -209,8 +209,8 @@ def register_argparse_arguments(parser: argparse.ArgumentParser) -> None:
             env="TWINE_USERNAME",
             required=False,
             help="The username to authenticate to the repository "
-            "(package index) as. (Can also be set via "
-            "%(env)s environment variable.)",
+            "(package index) as. Has no effect on PyPI or TestPyPI. "
+            "(Can also be set via %(env)s environment variable.)",
         )
         parser.add_argument(
             "-p",