cloud: add release notes 20250923 (#21823)

Author: hfxsd

tidb-cloud/tidb-cloud-release-notes.md

@@ -8,6 +8,24 @@ aliases: ['/tidbcloud/supported-tidb-versions','/tidbcloud/release-notes']
 
 This page lists the release notes of [TiDB Cloud](https://www.pingcap.com/tidb-cloud/) in 2025.
 
+## September 23, 2025
+
+**General changes**
+
+- **TiDB Cloud Dedicated**
+
+    - Support user-controlled splitting of `UPDATE` events in [TiDB Cloud Dedicated](/tidb-cloud/select-cluster-tier.md#tidb-cloud-dedicated) changefeeds.
+  
+        In TiDB Cloud Dedicated clusters, you can configure whether to keep `UPDATE` events as raw events or split them into separate `DELETE` and `INSERT` events. This feature provides greater flexibility for advanced replication scenarios. 
+  
+        This feature is supported only for non-SQL destinations such as Apache Kafka and Amazon S3. For more information, see [Sink to Apache Kafka](/tidb-cloud/changefeed-sink-to-apache-kafka.md), [Sink to Apache Pulsar](/tidb-cloud/changefeed-sink-to-apache-pulsar.md), and [Sink to Cloud Storage](/tidb-cloud/changefeed-sink-to-cloud-storage.md).
+
+        For more information about the splitting behavior, see [Split primary or unique key `UPDATE` events for non-MySQL sinks](https://docs.pingcap.com/tidb/stable/ticdc-split-update-behavior/#split-primary-or-unique-key-update-events-for-non-mysql-sinks).
+
+    - Provide a new node size for [TiDB Cloud Dedicated](/tidb-cloud/select-cluster-tier.md#tidb-cloud-dedicated) clusters hosted on Google Cloud: `32 vCPU, 64 GiB`.
+  
+        This new node size is available for TiDB nodes.
+
 ## September 16, 2025
 
 **General changes**