Application Cache, also known as AppCache, is deprecated.
Consider using the service worker Cache API instead.
To help migrate from AppCache to service workers, consider the sw-appcache-behavior library. This library generates a service-worker-based implementation of the behavior defined in an AppCache manifest.
See the URL Responds With a 200 When Offline audit reference for more resources on using service workers to make your site work offline.
The audit passes if no AppCache manifest is detected.