bake does not merge compose services/<service>/build/x-bake setting with serivice extensions

[cybercode]

In latest update to docker desktop, v 4.29.0 (145265), (other version info below). the x-bake key in the base compose file is not merged with the contents of the extension file if the key exists or is set. This is only seems to be true for the x-bake key. This worked at least as recently as docker desktop 4.24 (don't have any other versions available locally)

Below are examples of the compose.yml file and the output of docker builds bake --print:

extend.yml

services:
  extend:
    build:
      labels:
        - com.example.two=2
      x-bake:
        ssh: default
        platforms: linux/amd64

No x-bake key in base file

compose.yml

services:
  app:
    image: alpine:latest
    extends:
      file: ./extend.yml
      service: extend
    build:
      labels:
        - com.example.one=1

output

{
  "group": {
    "default": {
      "targets": [
        "app"
      ]
    }
  },
{
  "group": {
    "default": {
      "targets": [
        "app"
      ]
    }
  },
  "target": {
    "app": {
      "context": ".",
      "dockerfile": "Dockerfile",
      "labels": {
        "com.example.one": "1",
        "com.example.two": "2"
      },
      "tags": [
        "alpine:latest"
      ],
      "ssh": [
        "default"
      ],
      "platforms": [
        "linux/amd64"
      ]
    }
  }
}

with x-bake key in base file

compose.yml

services:
  app:
    image: alpine:latest
    extends:
      file: ./extend.yml
      service: extend
    build:
      labels:
        - com.example.one=1
      x-bake:

output

{
  "group": {
    "default": {
      "targets": [
        "app"
      ]
    }
  },
  "target": {
    "app": {
      "context": ".",
      "dockerfile": "Dockerfile",
      "labels": {
        "com.example.one": "1",
        "com.example.two": "2"
      },
      "tags": [
        "alpine:latest"
      ]
    }
  }
}

Environment

$ docker version
Client:
 Cloud integration: v1.0.35+desktop.13
 Version:           26.0.0
 API version:       1.45
 Go version:        go1.21.8
 Git commit:        2ae903e
 Built:             Wed Mar 20 15:14:46 2024
 OS/Arch:           darwin/arm64
 Context:           desktop-linux

Server: Docker Desktop 4.29.0 (145265)
 Engine:
  Version:          26.0.0
  API version:      1.45 (minimum version 1.24)
  Go version:       go1.21.8
  Git commit:       8b79278
  Built:            Wed Mar 20 15:18:02 2024
  OS/Arch:          linux/arm64
  Experimental:     false
 containerd:
  Version:          1.6.28
  GitCommit:        ae07eda36dd25f8a1b98dfbf587313b99c0190bb
 runc:
  Version:          1.1.12
  GitCommit:        v1.1.12-0-g51d5e94
 docker-init:
  Version:          0.19.0
  GitCommit:        de40ad0

$ docker buildx version
github.com/docker/buildx v0.13.1-desktop.1 2368b2ee41873b948cb607251cec573ed00f00f9