`generateEtags` config doesn't apply to `next/image` responses

Link to the code that reproduces this issue

https://github.com/akhilsugunan77/nextjs-etag-repro

To Reproduce

1. Start the production server (npm run build && npm start)

2. Request the any static chunk and inspect headers:

   curl -sI http://localhost:3000/_next/static/chunks/<hash>.js
   

   No ETag header — generateEtags: false is respected.

3. Request an optimized image and inspect headers:

   curl -sI "http://localhost:3000/_next/image?url=%2Ftest.jpg&w=256&q=75"
   

   ETag header is present — generateEtags: false is ignored.

Current vs. Expected behavior

I expected adding generateEtags: false in next config, will disable etag generation for all request. Currently it disables for pages and for static assets (_next/static/).

Static assets:

But for image request it still generates etag

Expected behaviour should be disabling etag generates for all requests.

Provide environment information

Operating System:
  Platform: darwin
  Arch: arm64
  Version: Darwin Kernel Version 25.0.0: Wed Sep 17 21:38:03 PDT 2025; root:xnu-12377.1.9~141/RELEASE_ARM64_T8112
  Available memory (MB): 24576
  Available CPU cores: 8
Binaries:
  Node: 24.14.0
  npm: 11.9.0
  Yarn: N/A
  pnpm: 10.14.0
Relevant Packages:
  next: 16.2.1-canary.1 // Latest available version is detected (16.2.1-canary.1).
  eslint-config-next: N/A
  react: 19.2.4
  react-dom: 19.2.4
  typescript: 5.9.3
Next.js Config:
  output: N/A

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

Image (next/image)

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

next build (local), next start (local), next dev (local)

Additional context

No response

Start with the reproduction repository and run npm run build && npm start, then compare the headers from the static chunk and /_next/image curl requests. Trace the next/image response handling and the generateEtags configuration path; done means optimized image responses omit ETag when the setting is false, with coverage for this case.