How to run Firebase 9?

Question

JavaScript

Now working with firebase 8 file firebase-messaging-sw.js

importScripts("https://www.gstatic.com/firebasejs/8.10.0/firebase-app.js");
importScripts("https://www.gstatic.com/firebasejs/8.10.0/firebase-messaging.js");

// https://firebase.google.com/docs/web/learn-more

// Initialize the Firebase app in the service worker by passing in the
// messagingSenderId.
firebase.initializeApp({});

// Retrieve an instance of Firebase Messaging so that it can handle background
// messages.
const messaging = firebase.messaging();

messaging.setBackgroundMessageHandler(function(payload) {
  
    let options = {
        body: payload.data.body,
        icon: payload.data.icon
    }

    let user = localStorage.getItem('VAFUserId'),
        data = JSON.parse(payload.data['gcm.notification.data']);

    // Search by hash
    if(data.users.find(el => el == user)) {
        return self.registration.showNotification(payload.data.title, options);
    }

});

Everything works fine, respectively, version 9 was released, where they offer to do everything through import

// JavaScript Document
import { initializeApp } from 'https://www.gstatic.com/firebasejs/9.1.3/firebase-app.js';
import { getMessaging, onBackgroundMessage } from 'https://www.gstatic.com/firebasejs/9.1.3/firebase-messaging-sw.js';

const firebaseApp = initializeApp({

});

const messaging = getMessaging(firebaseApp);

onBackgroundMessage(messaging, (payload) => {

    let options = {
        body: payload.data.body,
        icon: payload.data.icon
    }

    let user = localStorage.getItem('VAFUserId'),
        data = JSON.parse(payload.data['gcm.notification.data']);

    // Search by hash
    if(data.users.find(el => el == user)) {
        return self.registration.showNotification(payload.data.title, options);
    }

});

When registering a worker, I get the following error: " Uncaught SyntaxError: Cannot use import statement outside a module" which oezhit in a root - not clearly.
The application is not singlepage, but in PHP. Tell me how you can solve this problem or stay on version 8?