[Speed/Images] Mirage deprecation (#24174)

* [Speed] Mirage deprecation notice

* [Speed/Images] Mirage deprecation notice

Author: ToriLindsay

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

@@ -12,6 +12,11 @@ sidebar:
 
 import { FeatureTable, GlossaryTooltip, Render } from "~/components"
 
+:::caution[Deprecation notice]
+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.
 
 It does this by: