Link to the code that reproduces this issue

https://codesandbox.io/p/devbox/sleepy-lamport-go8s7s

To Reproduce

1.create a new file with filename a filename with Chinese-你好世界;
2.select in file input;
3.submit form;
4. the response filename is a filename with Chinese-你好世界

Current vs. Expected behavior

Expect get same file name.
and I found the root cause is here

The busboy default defParamCharset is latin1, if I submit chinese or other language with character not in latin1, the filename will garbled.
https://github.com/mscdex/busboy?tab=readme-ov-file#exports

But if I create an API with Route, I can use req.formdata() then the filename is correct.

Also, I tried

this config, then I can get correct filename with busboy, is that possible to set utf-8 to keep same behavior like Body.formdata()?

Provide environment information

Operating System:
  Platform: darwin
  Arch: x64
  Version: Darwin Kernel Version 23.6.0: Mon Jul 29 21:13:00 PDT 2024; root:xnu-10063.141.2~1/RELEASE_X86_64
  Available memory (MB): 32768
  Available CPU cores: 12
Binaries:
  Node: 20.17.0
  npm: 10.8.2
  Yarn: N/A
  pnpm: N/A
Relevant Packages:
  next: 14.2.13 // Latest available version is detected (14.2.13).
  eslint-config-next: 14.2.13
  react: 18.3.1
  react-dom: 18.3.1
  typescript: 5.5.4
Next.js Config:
  output: standalone

Which area(s) are affected? (Select all that apply)

Not sure, Runtime

Which stage(s) are affected? (Select all that apply)

next dev (local), next build (local), next start (local), Vercel (Deployed), Other (Deployed)

Additional context

This issue exist in v14 and v15 canary.