diff --git a/.buildkite/worker-blacklist b/.buildkite/worker-blacklist
index 7950d19db339..b4e20d327517 100644
--- a/.buildkite/worker-blacklist
+++ b/.buildkite/worker-blacklist
@@ -64,3 +64,9 @@ If remote user leaves room, changes device and rejoins we see update in sync
 uploading self-signing key notifies over federation
 Inbound federation can receive redacted events
 Outbound federation can request missing events
+
+# Flakey tests noticed as of https://github.com/matrix-org/synapse/pull/6409
+Can recv device messages over federation
+Device messages over federation wake up /sync
+Federation handles empty auth_events in state_ids sanely
+An event which redacts itself should be ignored