Although the userInfo.preferedLanguage is correctly filled in development, it stays null in production. This is really a pity because getting the preferedLanguage can be more than handy (ie: to set the correct locale for a date). There is a "strapi-admin-language" in the localStorage but it appears nowhere in the docs.

###Steps to reproduce:

Launch Strapi and open the devTools -> localStorage/userInfo under the Application tab

or

```js

import { auth } from "@strapi/helper-plugin";

const user = auth.get("userInfo");

console.log("user", user);

```