@vitejs/plugin-legacy fails after upgrading to Vite 7.3.2, but works when esbuild is overridden to 0.27.4

[GXX182]

Describe the bug

Describe the bug

After upgrading Vite to 7.3.2, @vitejs/plugin-legacy started failing during the
legacy downgrade/transformation flow.

I investigated the issue and found that forcing esbuild to 0.27.4 makes the problem
disappear:

{
  "overrides": {
    "esbuild": "0.27.4"
  }
}

So this appears to be a compatibility issue related to esbuild version resolution after
upgrading Vite.

Reproduction

Please provide a minimal reproduction repo if needed. I can prepare one.

Steps to reproduce

1. Upgrade Vite to 7.3.2
2. Use @vitejs/plugin-legacy
3. Run the build
4. See the failure
5. Add:

{
  "overrides": {
    "esbuild": "0.27.4"
  }
}

6. Reinstall dependencies
7. The problem disappears

Expected behavior

@vitejs/plugin-legacy should work correctly after upgrading to Vite 7.3.2 without
requiring an esbuild override.

Actual behavior

The build fails during the legacy transform step.

Error message

error during build:
[vite:esbuild-transpile] Transform failed with 1 error:
assets/_plugin-vue_export-helper-!~{014}~.js:3:13: ERROR: Transforming destructuring to the configured target environment ("chrome64", "edge79", "es2020", "firefox67", "safari12" + 2 overrides) is not supported yet
file: assets/_plugin-vue_export-helper-!~{014}~.js:3:13

Transforming destructuring to the configured target environment ("chrome64", "edge79", "es2020", "firefox67", "safari12" + 2 overrides) is not supported yet
1  |  const _export_sfc = (sfc, props) => {
2  |    const target = sfc.__vccOpts || sfc;
3  |    for (const [key, val] of props) {
   |               ^
4  |      target[key] = val;
5  |    }

    at failureErrorWithLog (D:\pro\lele-h5\leleyuyin-H5-vite\node_modules\esbuild\lib\main.js:1748:15)
    at D:\pro\lele-h5\leleyuyin-H5-vite\node_modules\esbuild\lib\main.js:1017:50
    at responseCallbacks.<computed> (D:\pro\lele-h5\leleyuyin-H5-vite\node_modules\esbuild\lib\main.js:884:9)
    at handleIncomingPacket (D:\pro\lele-h5\leleyuyin-H5-vite\node_modules\esbuild\lib\main.js:939:12)
    at Socket.readFromStdout (D:\pro\lele-h5\leleyuyin-H5-vite\node_modules\esbuild\lib\main.js:862:7)
    at Socket.emit (node:events:524:28)
    at addChunk (node:internal/streams/readable:561:12)
    at readableAddChunkPushByteMode (node:internal/streams/readable:512:3)
    at Readable.push (node:internal/streams/readable:392:5)
    at Pipe.onStreamRead (node:internal/stream_base_commons:191:23)

Environment

• Vite: 7.3.2
• @vitejs/plugin-legacy: ^7.2.1
• esbuild: ^0.28.0
• Node: 20.19.0
• Package manager: npm
• OS: Windows

Additional context

I also found related discussion/issues in the esbuild repository, which made me suspect
this may be caused by an esbuild compatibility change.
If helpful, I can provide the exact error stack and a minimal reproduction repository.

Reproduction

https://github.com/GXX182/vite-legacy-bug

Steps to reproduce

No response

System Info

System:
    OS: Windows 10 10.0.19045
    CPU: (12) x64 11th Gen Intel(R) Core(TM) i5-11400 @ 2.60GHz
    Memory: 11.60 GB / 31.82 GB
  Binaries:
    Node: 20.19.0 - C:\Program Files\nodejs\node.EXE
    npm: 10.8.2 - C:\Program Files\nodejs\npm.CMD
    pnpm: 10.22.0 - C:\Program Files\nodejs\pnpm.CMD
  Browsers:
    Chrome: 146.0.7680.178
    Edge: Chromium (140.0.3485.54)
    Internet Explorer: 11.0.19041.4355
  npmPackages:
    @vitejs/plugin-legacy: ^7.2.1 => 7.2.1
    @vitejs/plugin-vue: ^6.0.5 => 6.0.6
    vite: 7.3.2 => 7.3.2

Used Package Manager

npm

Logs

No response

Validations

• Follow our Code of Conduct
• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• Make sure this is a Vite issue and not a framework-specific issue. For example, if it's a Vue SFC related bug, it should likely be reported to vuejs/core instead.
• Check that this is a concrete bug. For Q&A open a GitHub Discussion or join our Discord Chat Server.
• The provided reproduction is a minimal reproducible example of the bug.

[GXX182]

Adding a quick clarification to make reproduction easier:

The linked repo already reproduces the issue on a clean setup:
https://github.com/GXX182/vite-legacy-bug

Steps:

1. npm install

2. npm run build → fails during legacy transform

3. Add:

   "overrides": {
     "esbuild": "0.27.4"
   }

4. Reinstall & build again → succeeds

Legacy config used:

legacy({
  targets: ['Android >= 8', 'iOS >= 12', 'Chrome >= 60'],
  additionalLegacyPolyfills: ['regenerator-runtime/runtime'],
})

This appears to be related to the esbuild version resolved in Vite 7.3.2, rather than project-specific code.