- Kubenet: added HostPort IPv6 support.  HostPortManager: operates only with one IP family, failing if receives port mapping entries with different IP families.  HostPortSyncer: operates only with one IP family, skipping portmap entries with different IP families ([#80854](https://github.com/kubernetes/kubernetes/pull/80854), [@aojea](https://github.com/aojea))

- Client-go now exposes two new metrics to monitor the client-go logic that
  generate http.Transports for the clients.
  
  - `rest_client_transport_cache_entries` is a gauge metric
  with the number of existing entries in the internal cache
  
  - `rest_client_transport_create_calls_total` is a counter
  that increments each time a new transport is created, storing

* Check if container memory stats are available before accessing it ([#77656](https://github.com/kubernetes/kubernetes/pull/77656), [@yastij](https://github.com/yastij))
* Fixes segmentation fault issue with Protobuf library when log entries are deeply nested. ([#77224](https://github.com/kubernetes/kubernetes/pull/77224), [@qingling128](https://github.com/qingling128))

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* Fix a bug that prevents client-go metrics from being registered in prometheus in multiple components. ([#53434](https://github.com/kubernetes/kubernetes/pull/53434), [@crassirostris](https://github.com/crassirostris))
* Webhook always retries connection reset error. ([#53947](https://github.com/kubernetes/kubernetes/pull/53947), [@crassirostris](https://github.com/crassirostris))

* If a required flag is not provided to a command, the user will only see the required flag error message, instead of the entire usage menu. ([#86693](https://github.com/kubernetes/kubernetes/pull/86693), [@sallyom](https://github.com/sallyom))