diff --git a/changelog.d/17167.feature b/changelog.d/17167.feature
index 156388425b..5ad31db974 100644
--- a/changelog.d/17167.feature
+++ b/changelog.d/17167.feature
@@ -1 +1 @@
-Add experimental [MSC3575](https://github.com/matrix-org/matrix-spec-proposals/pull/3575) Sliding Sync `/sync/e2ee` endpoint for To-Device messages.
+Add experimental [MSC3575](https://github.com/matrix-org/matrix-spec-proposals/pull/3575) Sliding Sync `/sync/e2ee` endpoint for To-Device messages and device encryption info.
diff --git a/synapse/handlers/sync.py b/synapse/handlers/sync.py
index 46eeaa1dbb..9ac9280156 100644
--- a/synapse/handlers/sync.py
+++ b/synapse/handlers/sync.py
@@ -1845,7 +1845,6 @@ class SyncHandler:
         At the end, we transfer data from the `sync_result_builder` to a new `E2eeSyncResult`
         instance to signify that the sync calculation is complete.
         """
-
         user_id = sync_config.user.to_string()
         app_service = self.store.get_app_service_by_user_id(user_id)
         if app_service:
@@ -1869,6 +1868,11 @@ class SyncHandler:
         if include_device_list_updates:
             # Note that _generate_sync_entry_for_rooms sets sync_result_builder.joined, which
             # is used in calculate_user_changes below.
+            #
+            # TODO: Running `_generate_sync_entry_for_rooms()` is a lot of work just to
+            # figure out the membership changes/derived info needed for
+            # `_generate_sync_entry_for_device_list()`. In the future, we should try to
+            # refactor this away.
             (
                 newly_joined_rooms,
                 newly_left_rooms,