Nuxt Middleware: Manual refresh of page causes Vuex store property to be "null" -- how to fix?

I've got an app that uses middleware to try and redirect a user to another page if he is not logged in.

The page that uses it is set up like so:

pages/upload.vue:

export default {
  name: 'Upload',
  middleware: 'redirect',
  ...etc...

The middleware/redirect.js file looks like so:

export default function ({ redirect, store }) {
  const isLoggedIn = store.getters.isLoggedIn
  console.log(isLoggedIn)
  // if (!isLoggedIn) {
  //   redirect({ name: 'login' })
  // }
}

Navigating TO the upload page works fine and the console is logged with true from the middleware, however, doing a manual page refresh or typing the page upload URL in the browser causes the console.log(isLoggedIn) to output false.

So, here is my store/getters.js file logic:

export default {
  isLoggedIn: (state) => {
    try {
      return state.userProfile.uid !== null
    } catch {
      return false
    }
  }
}

store/state.js is like so:

export default () => ({
    authUser: null,
    userProfile: null
  })

It looks like the user state is null on initial SSR load. I am using a custom plugin called auth like so:

plugins/auth.js: and loaded it in nuxt.config.js like so:

plugins: [
{ src: '~/plugins/auth.js' }
]

import { onAuthStateChanged, getAuth } from 'firebase/auth'
import { doc, getDoc } from 'firebase/firestore'
import { db } from '~/plugins/firebase'

export default (context, inject) => {
  const auth = getAuth()
  inject(
    'authObserver',
    onAuthStateChanged(auth, async (user) => {
      console.log('user state:', user)
      if (user) {
      ...etc...
}

So, all together, the above code outputs the following console log (note the null user state on SSR!):

OK, so obviously we should not care about SSR for client logic like this as it's not needed for crawlers, so how should I write the logic for the middleware to check whether a user is logged in or not? That way I can redirect him to login page to login before proceeding to upload page.

Thanks!