We need to add a holdback experiment that disables all data saver features. This includes (i) disabling fetching of resources via proxy, (ii) disabling triggering of any previews that are conditioned on data saver being enabled (iii) Returning false for navigator.connection.saveData JavaScript API (iv) Not sending "save-data:on" client hint (v) Not disabling autoplay or preload of non-muted videos.

However, in the data saver settings UI, we would still want to show users that data saver is enabled. So, I think one way to do this, might be to split IsDataReductionProxyEnabled() to two methods: One that will be used by consumers for triggering different features, and other for the purpose of UI.