docs: clarify Astro.url and params normalization

Author: Prayaksh

src/content/docs/en/reference/api-reference.mdx

@@ -137,6 +137,8 @@ In static builds, this will be the `params` returned by `getStaticPaths()` used
 
 When routes are rendered on demand, `params` can be any value matching the path segments in the dynamic route pattern.
 
+`params` values are automatically decoded from route pathnames.
+
 ```astro title="src/pages/posts/[id].astro" "Astro.params"
 ---
 import { getPost } from '../api';
@@ -165,7 +167,9 @@ See also: [`params`](/en/reference/routing-reference/#params)
 
 `url` is a [URL](https://developer.mozilla.org/en-US/docs/Web/API/URL) object constructed from the current `request.url` value. It is useful for interacting with individual properties of the request URL, like pathname and origin. 
 
-`Astro.url` is equivalent to doing `new URL(Astro.request.url)`.
+`Astro.url` is a normalized `URL` instance derived from `Astro.request.url`.
+
+In Astro v6, the pathname is partially decoded during route normalization, so `Astro.url.pathname` may differ from `new URL(Astro.request.url).pathname` for percent-encoded route segments.
 
 `url` will be a `localhost` URL in dev mode. When building a site, prerendered routes will receive a URL based on the [`site`](/en/reference/configuration-reference/#site) and [`base`](/en/reference/configuration-reference/#base) options. If `site` is not configured, prerendered pages will receive a `localhost` URL during builds as well.