diff --git a/src/Core/Settings.cpp b/src/Core/Settings.cpp
index 7eb4d9f8055c..eb4fb2bcf8a7 100644
--- a/src/Core/Settings.cpp
+++ b/src/Core/Settings.cpp
@@ -8062,11 +8062,15 @@ To survive a long transient outage (e.g. object storage downtime), raise `export
     DECLARE(UInt64, export_merge_tree_partition_retry_max_backoff_seconds, 300, R"(
 Maximum delay (in seconds) between retries of a failed part export in an export partition task. Caps the exponential growth controlled by `export_merge_tree_partition_retry_initial_backoff_seconds`.
 )", 0) \
-    DECLARE(UInt64, export_merge_tree_partition_task_timeout_seconds, 3600, R"(
+    DECLARE(UInt64, export_merge_tree_partition_task_timeout_seconds, 86400, R"(
 Maximum wall-clock duration (in seconds) an export partition task is allowed to remain in the PENDING state before it is auto-killed by the background cleanup loop.
 The timeout is measured from the manifest's create_time. Set to 0 to disable the timeout.
 When the timeout is exceeded the task transitions to KILLED (same terminal state as `KILL QUERY ... EXPORT PARTITION`), and `last_exception` is populated with a timeout reason.
 
+IMPORTANT: In case the storage is managed by a 3rd party application that cleans up old manifest files, it is important that the TTL of such files are greater than the timeout of export partition tasks.
+If it is not configured in such a way, it is possible to accidentally duplicate data in the extremely rare case a ClickHouse node is the only node working on a given export task, commits the data to Iceberg, crashes before marking the task as done and only boots up after the manifest cleanup has deleted the commit manifest.
+In such scenario, ClickHouse would attempt to commit those files again producing duplicates. 
+
 Notes:
 - Enforcement is best-effort: actual kill latency is bounded by one manifest-updater poll cycle (~30s) plus ZooKeeper watch propagation.
 )", 0) \