diff --git a/CHANGES.md b/CHANGES.md
index e5177e714..e9872ff05 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -5,7 +5,7 @@ Bugfixes
 --------
 
 - Fix a regression in v1.21.0rc1 which broke thumbnails of remote media. ([\#8438](https://github.com/matrix-org/synapse/issues/8438))
-- Do not expose the experimental `uk.half-shot.msc2778.login.application_service` flow in the login API. ([\#8440](https://github.com/matrix-org/synapse/issues/8440))
+- Do not expose the experimental `uk.half-shot.msc2778.login.application_service` flow in the login API, which caused a compatibility problem with Element iOS. ([\#8440](https://github.com/matrix-org/synapse/issues/8440))
 - Fix malformed log line in new federation "catch up" logic. ([\#8442](https://github.com/matrix-org/synapse/issues/8442))
 - Convert additional templates from inline HTML to Jinja2 templates. ([\#8444](https://github.com/matrix-org/synapse/issues/8444))
 - Fix DB query on startup for negative streams which caused long start up times. Introduced in #8374. ([\#8447](https://github.com/matrix-org/synapse/issues/8447))