Add self-diagnosis guide for Dag version inflation in FAQ

airflow-core/docs/faq.rst

@@ -379,6 +379,27 @@ How to avoid version inflation
           bash_command="echo {{ var.value.my_variable }}",
       )
 
+How to diagnose version inflation yourself
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+
+If your Dag version keeps increasing and it is not obvious which constructor argument is to blame, you
+can identify the changing field by inspecting the serialized Dag rows directly.
+
+The most reliable way is to query the ``serialized_dag`` table in the metadata database and compare how
+the serialized payload differs between two consecutive versions of the same Dag. The column that stores
+the serialized Dag holds the structured data that Airflow hashes to decide whether a new version is
+needed, so diffing two rows shows you exactly which field changed between parses.
+
+Once you spot the changing field, trace it back to the place in your Dag file where it is set, and
+replace the dynamic value with a deterministic one — for example, a fixed ``datetime`` literal, a Jinja
+template evaluated at execution time, or an Airflow Variable resolved via template. See
+`How to avoid version inflation`_ for concrete patterns.
+
+If you cannot tie the changing field to anything in your Dag code, and the value appears to come from
+Airflow itself (for example, an internal attribute that should be stable across parses), please report
+it as a bug at https://github.com/apache/airflow/issues. Include both serialized Dag payloads (or the
+relevant diff) and the Airflow version so maintainers can reproduce the issue.
+
 Dag version inflation detection
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