diff --git a/docs/changelog/2631.doc.rst b/docs/changelog/2631.doc.rst
new file mode 100644
index 0000000000..4df85bea57
--- /dev/null
+++ b/docs/changelog/2631.doc.rst
@@ -0,0 +1 @@
+Document that ``-U`` is not longer a when defining dependencies via ``deps`` - by :user:`jugmac00`.
diff --git a/docs/faq.rst b/docs/faq.rst
index 2c7495edf6..887edb3b93 100644
--- a/docs/faq.rst
+++ b/docs/faq.rst
@@ -44,6 +44,9 @@ tox 4 - changed INI rules
           ALPHA
           BETA
 
+- When defining dependencies, with tox 4 you can no longer use the ``-U`` flag, e.g. ``deps = -Ur requirements.txt`` is
+  no longer valid. As tox creates a new environment, ``-U`` is not needed anyway.
+
 tox 4 - known regressions
 +++++++++++++++++++++++++