[Vuejs]-Display RSS Feed or API on Vue application

Your backend gives permission, using CORS, for any origin to read data from it.

Your frontend is asking for the RSS data directly from Google. It isn’t going anywhere near your backend.

Google aren’t using CORS to give your frontend permission to read its data.

You need to change your frontend so it asks your backend for the data, and you need to change your backend so it provides the frontend with that data (which will mean having the backend fetch it from Google (and likely keep a local cache of it)).