Example of how to initialize firebase@exp

firebaseClient.js

import { initializeApp } from 'firebase/app';
import { getAuth, onAuthStateChanged } from "firebase/auth";
import { getFirestore } from 'firebase/firestore';
import { getStorage } from "firebase/storage";

let ssrAuthed = window.ssrUser;

const firebaseConfig = {
  //   ...
};

const firebase = window.firebase || initializeApp(firebaseConfig);
window.firebase = firebase;
const auth = getAuth(firebase);
const firestore = getFirestore(firebase);
const storage = getStorage(firebase);

onAuthStateChanged(auth, (u) => {
  console.log({ ssrAuthed, u });
});

export {
  firebase,
  auth,
  firestore,
  storage
};

@thormuller Instead of using the window object to save the app instance, I have used this and it seems to work.

import { initializeApp, getApp, getApps } from 'firebase/app';

const firebase = (getApps().length && getApp()) || initializeApp(firebaseConfig);

Thank you both. To @acoyfellow's point, there was just a bit update to SK and an update to Vite. I'm in the midst of that update, so perhaps this is an artifact of the swirl. I'll definitely try your solution if the update doesn't fix things.