- Change `pod_preemption_victims` metric from Gauge to Histogram. ([#83603](https://github.com/kubernetes/kubernetes/pull/83603), [@Tabrizian](https://github.com/Tabrizian))
- Following metrics from kubelet are now marked as with the ALPHA stability level:

    - `rest_client_certificate_expiration_seconds` a gauge reporting the lifetime of the current client certificate. Reports the time of expiry in seconds since January 1, 1970 UTC.

- `transformation_latencies_microseconds` -> `transformation_latencies_seconds`
- `data_key_generation_latencies_microseconds` -> `data_key_generation_latencies_seconds`

## Notable Features

- Increased the histogram resolution of the API server client certificate  to accommodate short-lived (< 6h) client certificates. ([#74806](https://github.com/kubernetes/kubernetes/pull/74806), [@mxinden](https://github.com/mxinden))

- A new `pod_status_sync_duration_seconds` histogram is reported at alpha metrics stability that estimates how long the Kubelet takes to write a pod status change once it is detected. ([#107896](https://github.com/kubernetes/kubernetes/pull/107896), [@smarterclayton](https://github.com/smarterclayton))...

    If an SLO/alert has been defined based on `volume_operation_total_seconds`, it might get violated because of the more accurate metric might be significantly larger than previously reported. The metric is defined to be a histogram and the new semantic could change the distribution. ([#78061](https://github.com/kubernetes/kubernetes/pull/78061), [@yuxiangqian](https://github.com/yuxiangqian))

   ([#123611](https://github.com/kubernetes/kubernetes/pull/123611), [@ritazh](https://github.com/ritazh))

- A new histogram metric to track the time it took to delete a job by the `TTLAfterFinished` controller ([#98676](https://github.com/kubernetes/kubernetes/pull/98676), [@ahg-g](https://github.com/ahg-g))

- The `priority_level_request_utilization` metric histogram is adjusted so that for the cases where `phase=waiting` the denominator is the cumulative capacity of all of the priority level's queues.

- Add a namespace label for all `apiserver_admission_* metrics`.
  Expand the histogram range to 0-10s for all `apiserver_admission_*_duration_seconds` metrics. ([#101208](https://github.com/kubernetes/kubernetes/pull/101208), [@voutcn](https://github.com/voutcn))

- Client-go: add new histogram metric to record the size of the requests and responses. ([#108296](https://github.com/kubernetes/kubernetes/pull/108296), [@aojea](https://github.com/aojea))