## Changes by Kind

### Feature

- Kubernetes is now built with go 1.21.9
  - update debian-base/set-cap to bookworm-v1.0.2 ([#124198](https://github.com/kubernetes/kubernetes/pull/124198), [@cpanato](https://github.com/cpanato)) [SIG API Machinery, Architecture, Release and Testing]

### Bug or Regression

## Changelog since v1.8.14

### Action Required

* ACTION REQUIRED: Kubernetes JSON deserializer is now case-sensitive to restore compatibility with pre-1.8 servers. If your config files contains fields with wrong case, the config files will be now invalid. ([#65410](https://github.com/kubernetes/kubernetes/pull/65410), [@nikhita](https://github.com/nikhita))

### Other notable changes

### Other (Cleanup or Flake)

- Build: Update Debian base images
  - debian-base:v2.1.3
  - debian-iptables:v12.1.2
  - debian-hyperkube-base:v1.1.3 ([#93924](https://github.com/kubernetes/kubernetes/pull/93924), [@justaugustus](https://github.com/justaugustus)) [SIG API Machinery, Cluster Lifecycle and Release]

* Bump up version number of debian-base, debian-hyperkube-base and debian-iptables.  ([#67026](https://github.com/kubernetes/kubernetes/pull/67026), [@satyasm](https://github.com/satyasm))
    * Also updates dependencies of users of debian-base.
    * debian-base version 0.3.1 is already available.

### Other (Cleanup or Flake)

- Build: Update Debian base images
  - debian-base:v2.1.3
  - debian-iptables:v12.1.2
  - debian-hyperkube-base:v1.1.3 ([#93754](https://github.com/kubernetes/kubernetes/pull/93754), [@justaugustus](https://github.com/justaugustus)) [SIG API Machinery, Cluster Lifecycle, Release and Testing]

- Improved FormatMap: Improves performance by about 4x, or nearly 2x in the worst case ([#112661](https://github.com/kubernetes/kubernetes/pull/112661), [@aimuz](https://github.com/aimuz)) [SIG Node]
- Improved misleading message, in case of no metrics received for the `HPA` controlled pods. ([#114740](https://github.com/kubernetes/kubernetes/pull/114740), [@kushagra98](https://github.com/kushagra98))

* Bump up version number of debian-base, debian-hyperkube-base and debian-iptables.  ([#67026](https://github.com/kubernetes/kubernetes/pull/67026), [@satyasm](https://github.com/satyasm))
    * Also updates dependencies of users of debian-base.
    * debian-base version 0.3.1 is already available.

- Base-images: Update to debian-iptables:buster-v1.4.0
  - Uses iptables 1.8.5
  - base-images: Update to debian-base:buster-v1.3.0
  - cluster/images/etcd: Build etcd:3.4.13-2 image
    - Uses debian-base:buster-v1.3.0 ([#98401](https://github.com/kubernetes/kubernetes/pull/98401), [@pacoxu](https://github.com/pacoxu)) [SIG Testing]

* Bump up version number of debian-base, debian-hyperkube-base and debian-iptables.  ([#67026](https://github.com/kubernetes/kubernetes/pull/67026), [@satyasm](https://github.com/satyasm))
    * Also updates dependencies of users of debian-base.
    * debian-base version 0.3.1 is already available.

### SIG Release

- Use debian-base instead of busybox as base image for server images ([#70245](https://github.com/kubernetes/kubernetes/pull/70245), [@ixdy](https://github.com/ixdy))