Turbopack causes `req instanceof NextRequest` to fail in `nodejs` middleware

### Link to the code that reproduces this issue https://github.com/SimonVadier/repro-turbopack-nodejs-middleware ### To Reproduce 1. Start the application with `next dev` 2. Visit the app 3. Observe console log `Request is an instance of NextRequest` 4. Start the application with `next dev --turbopack` 5. Visit the app 6. Observe console log `Request is not an instance of NextRequest` ### Current vs. Expected behavior When using Turbopack in dev mode, `request instanceof NextRequest ` returns false in a `nodejs` middleware, while it returns true with the standard dev server. This is problematic because some libraries rely on this check to determine how to process the request object. (https://github.com/auth0/nextjs-auth0/issues/2253) The request object provided by Turbopack seems to have the same shape and functionality as `NextRequest`, but it fails the instanceof check. ### Provide environment information ```bash Operating System: Platform: linux Arch: x64 Version: #1 SMP PREEMPT_DYNAMIC Thu Aug 21 06:22:32 EDT 2025 Available memory (MB): 15732 Available CPU cores: 12 Binaries: Node: 24.5.0 npm: 11.5.1 Yarn: 1.22.22 pnpm: 10.14.0 Relevant Packages: next: 15.5.2 // Latest available version is detected (15.5.2). eslint-config-next: N/A react: 19.1.1 react-dom: 19.1.1 typescript: N/A Next.js Config: output: N/A ``` ### Which area(s) are affected? (Select all that apply) Middleware ### Which stage(s) are affected? (Select all that apply) next dev (local) ### Additional context _No response_ _{[PACK-5361](https://linear.app/vercel/issue/PACK-5361/turbopack-causes-req-instanceof-nextrequest-to-fail-in-nodejs)}