Next.js returns HTML instead of JSON for _next/data requests

### Link to the code that reproduces this issue https://github.com/arichard-info/next-rewrite-middleware ### To Reproduce 1. Clone the repo 2. `npm run build` 3. `npm run start` 4. Open the network tab and rollover the link 5. Open the _next/data request in a new tab (for example `http://localhost:3000/_next/data/Wyr4K4y9f6V6FjKlwRrH5ee/fr/nice-public-path.json`) => you get the page JSON 6. Change the buildId in the request (for example `http://localhost:3000/_next/data/test/fr/nice-public-path.json` => you get the page HTML Conditions to reproduce : - Having rewrite rules in the middleware - Having `i18n` configuration in `next.config.js` ### Current vs. Expected behavior When using middleware rewrites + i18n, mismatches of buildId are not well catched for _next/data requests. On client-side navigation, the _next/data requests with invalid buildId returns the page HTML instead of a 404. The expected behavior is to get a 404. The _next/data requests should never return HTML content This causes issues for example when you have a custom cache configuration : When you are behind a CDN cache and navigate between two pages, if _next/data calls contains the previous buildId, you're getting a broken page ### Verify canary release - [X] I verified that the issue exists in the latest Next.js canary release ### Provide environment information ```bash Operating System: Platform: darwin Arch: x64 Version: Darwin Kernel Version 22.3.0: Mon Jan 30 20:42:11 PST 2023; root:xnu-8792.81.3~2/RELEASE_X86_64 Binaries: Node: 18.19.0 npm: 10.2.3 Yarn: 1.22.19 pnpm: 8.6.9 Relevant Packages: next: 14.0.4 eslint-config-next: 14.0.4 react: 18.2.0 react-dom: 18.2.0 typescript: 5.3.3 Next.js Config: output: N/A ``` ### Which area(s) are affected? (Select all that apply) Middleware / Edge (API routes, runtime), Routing (next/router, next/navigation, next/link) ### Additional context _No response_