[mob][photos] Comment

mobile/lib/services/machine_learning/face_ml/face_clustering/face_clustering_service.dart

@@ -503,6 +503,7 @@ class FaceClusteringService {
       if (i % 250 == 0) {
         log("[ClusterIsolate] ${DateTime.now()} Processed ${offset != null ? i + offset : i} faces");
       }
+      // WARNING: The loop below is now O(n^2) so be very careful with anything you put in there!
       for (int j = i - 1; j >= 0; j--) {
         final double distance = 1 -
               sortedFaceInfos[i]