high85%
`next start` built-in compression never applies to Route Handlers (including metadata routes) — sitemap.xml served uncompressed
In Next.js 16.2.10, when using `next start`, page renders are correctly compressed by the built-in `compression` middleware, but all Route Handler responses (including static/prerendered metadata routes and dynamic route handlers) are sent without any `Content-Encoding`. This occurs even when the response body is well above the 1KB compression threshold and the content type is compressible (e.g., `application/xml`). The issue violates the official documentation's promise that Next.js compresses "rendered content and static files" by default, leading to wasted bandwidth and degraded performance for sitemaps, JSON APIs, and other large Route Handler responses in self-hosted environments.