Use vue3-cookies in custom plugin

I want to use vue3-cookies in my custom plugin, but whatever I do I keep getting undefined.

MyPlugin.js

export default {
    install: (app, options) => {
        app.config.globalProperties.$MyPlugin= {
            someFunction() {
                console.log(app.cookie);
                console.log(app.cookies);
                console.log(app.$cookies);
            }
        }
    },
};

app.js

import {createApp} from 'vue';
import VueCookies from 'vue3-cookies'
import MyPlugin from "./plugins/MyPlugin";

const app = createApp({});
app.use(VueCookies)
app.use(MyPlugin)
const mountedApp = app.mount('#app');

What am I missing or doing wrong?