Manifest contains name The name property identifies your app and is required. Learn more.
Manifest contains background_color When your app launches from a user's homescreen, the browser uses background_color to paint the background of the browser while your app loads for a smooth transition experience. Learn more.
I think this webpack plugin is not related to web-app manifests. It's purpose is to generate an asset manifest which maps hashed filenames to original file-names.
Lighthouse failed on the following