Update 7.4.0 release notes to add deprecation plan (#15052) (#15058)

releases/release-7.4.0.md

@@ -321,6 +321,11 @@ Quick access: [Quick start](https://docs.pingcap.com/tidb/v7.4/quick-start-with-
 | TiCDC | [`large-message-handle-compression`](/ticdc/ticdc-sink-to-kafka.md#ticdc-data-compression) | Newly added | Controls whether to enable compression during encoding. The default value is empty, which means not enabled. |
 | TiCDC | [`large-message-handle-option`](/ticdc/ticdc-sink-to-kafka.md#send-large-messages-to-external-storage) | Modified | This configuration item adds a new value `claim-check`. When it is set to `claim-check`, TiCDC Kafka sink supports sending the message to external storage when the message size exceeds the limit and sends a message to Kafka containing the address of this large message in external storage. |
 
+## Deprecated features
+
++ [Mydumper](https://docs.pingcap.com/tidb/v4.0/mydumper-overview) will be deprecated in v7.5.0 and most of its features have been replaced by [Dumpling](/dumpling-overview.md). It is strongly recommended that you use Dumpling instead of mydumper.
++ TiKV-importer will be deprecated in v7.5.0. It is strongly recommended that you use the [Physical Import Mode of TiDB Lightning](/tidb-lightning/tidb-lightning-physical-import-mode.md) as an alternative.
+
 ## Improvements
 
 + TiDB