[nuxt] proxyRequest with multiple 'set-cookie' headers gets merged into one header

[Mokkapps]

Environment

Nuxt: 3.4.3
Node: 18.14.2

Reproduction

https://stackblitz.com/github/Mokkapps/nuxt-multiple-set-cookie?file=server/api/upstream.ts

Describe the bug

Current Behaviour

Only one set-cookie is returned from the proxyRequest response:

export default defineEventHandler((event) => {
  return proxyRequest(
    event,
    "https://7dzqb4dvrf.execute-api.eu-central-1.amazonaws.com/dev"
  );
});

The endpoint response which contains multiple set-cookie response headers:

The proxyRequest response only contains the last set-cookie header:

Expected Behaviour

proxyRequest proxies all set-cookie response headers

Additional context

No response

Logs

No response

[PunkPengu]

same problem here :( hope it will get fixed soon!

[oleghalin]

See unjs/nitro#989

[pi0]

Hi. For proxy we do split cookies but there was a bug with node fetch (#408).

Please let me know if this still needs investigation in h3. (nitro PR is separate issue to track)