diff --git a/tests/sanity/ignore-2.21.txt b/tests/sanity/ignore-2.21.txt
new file mode 100644
index 00000000..12e0b26f
--- /dev/null
+++ b/tests/sanity/ignore-2.21.txt
@@ -0,0 +1 @@
+plugins/modules/docker_container_copy_into.py validate-modules:undocumented-parameter # _max_file_size_for_diff is used by the action plugin
diff --git a/tests/sanity/ignore-2.21.txt.license b/tests/sanity/ignore-2.21.txt.license
new file mode 100644
index 00000000..edff8c76
--- /dev/null
+++ b/tests/sanity/ignore-2.21.txt.license
@@ -0,0 +1,3 @@
+GNU General Public License v3.0+ (see LICENSES/GPL-3.0-or-later.txt or https://www.gnu.org/licenses/gpl-3.0.txt)
+SPDX-License-Identifier: GPL-3.0-or-later
+SPDX-FileCopyrightText: Ansible Project