If this happens try to set useCorsProxy to false in your feed config. Like this:

modules: [ { module: "newsfeed", position: "top_right", config: { feeds: [ { title: "tagesschau.de", url: "https://www.tagesschau.de/xml/rss2/", useCorsProxy: false } ] } }, { module: "MMM-News-QR", position: "top_right", config: { updateType: "push", interval: 2000, animationSpeed: 2500, colorDark: "#fff", colorLight: "#000", imageSize: 150 } } ]