Clarified the message by adding code needs to be updated.

Author: tangix

user_guide_src/source/changelogs/v4.0.4.rst

@@ -52,7 +52,7 @@ Bugs Fixed:
 - Fixed bug in Image GD handler that would try to compress images twice in certain cases
 - Ensure get translation output logic work on selected locale, dashed locale, and fallback "en"
 - Fix is_unique/is_not_unique validation called on POST/PUT via API in Postgresql
-- Added ``$arguments`` parameter to after() and before() in FilterInterface
+- Added ``$arguments`` parameter to after() and before() in FilterInterface. This is a breaking change, so all code implementing the FilterInterface must be updated
 - Fixed a bug where filter arguments were not passed to after()