diff --git a/changelogs/client_server/newsfragments/2101.breaking b/changelogs/client_server/newsfragments/2101.breaking
index 84c645ab6..bcbdcd553 100644
--- a/changelogs/client_server/newsfragments/2101.breaking
+++ b/changelogs/client_server/newsfragments/2101.breaking
@@ -1 +1 @@
-Add a new ``submit_url`` field to the response of various `.../requestToken` endpoints.
+Breaking change: Add a new ``submit_url`` field to the response of various `.../requestToken` endpoints. Clients should request a token from the user to submit 3PID validation when they received this field. Older clients will not know about this field and thus may display a deceptive message thinking that validation will be handled out of bounds.