[Speed/Images] Mirage deprecation notice

Author: ToriLindsay

src/content/docs/speed/optimization/images/mirage.mdx

@@ -13,7 +13,8 @@ sidebar:
 import { FeatureTable, GlossaryTooltip, Render } from "~/components"
 
 :::caution[Deprecation notice]
-Mirage is being deprecated and will be removed on XXXX-XX-XX. Cloudflare recommends using [lazy loading](/images/tutorials/optimize-mobile-viewing/#lazy-loading) as an alternative to Mirage to optimize the images on your webpages for mobile viewing.
+Mirage is being deprecated and will be removed on September 15, 2025.
+As an alternative, Cloudflare recommends using [lazy loading](/images/tutorials/optimize-mobile-viewing/) and [responsive images](/images/transform-images/make-responsive-images/) to optimize image performance for all devices.
 :::
 
 Cloudflare Mirage reduces bandwidth used by images in mobile browsers. It can accelerate loading of image-heavy websites on very slow mobile connections and HTTP/1.