I created that before miniflux added some basic filtering.
The difference from the built-in filtering is that the built-in filtering filters articles out BEFORE adding them to the DB, whereas this just marks them as read, so you can still go to "All" and see them if you wish.
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The new version adds a UI for managing filters. The UI "borrows" the css & javascript from Miniflux, so the look & feel is (almost) exactly the same as the main app!