diff --git a/ingestor/managers/ingestor_manager.py b/ingestor/managers/ingestor_manager.py
index a141e3c..4b3d8f8 100644
--- a/ingestor/managers/ingestor_manager.py
+++ b/ingestor/managers/ingestor_manager.py
@@ -561,8 +561,9 @@ class IngestorManager(SientiaMonitoring):
         """
 
         # list() snapshots the readers: the loop awaits, so a reader added or removed
-        # meanwhile must not break the iteration.
-        for server, reader in list(self.opc_managers.items()):  # NOSONAR
+        # meanwhile must not break the iteration. SonarQube flags it as an unnecessary
+        # list() (S7504); the issue is accepted in SonarQube for this reason.
+        for server, reader in list(self.opc_managers.items()):
             if slot in reader.subscriptions:
                 await self._unsubscribe_reader(server, reader, slot)