firebaseによるAsyncStorage警告はgetReactNativePersistenceで解決できる

Warning: Async Storage has been extracted from react-native core
and will be removed in a future release. It can now be installed
and imported from '@react-native-community/async-storage' 
instead of 'react-native'. See https://github.com/react-native-community/react-native-async-storage

import { getApp, getApps, initializeApp } from "firebase/app"
import { getAuth, initializeAuth } from "firebase/auth"
import AsyncStorage from "@react-native-async-storage/async-storage"
import { getReactNativePersistence } from 'firebase/auth/react-native'

const initalizeFirebase = () => {
  const app = initializeApp(FIREBASE_CONFIG)
  
  // ↓この設定を追加
  initializeAuth(app, {
    persistence: getReactNativePersistence(AsyncStorage)
  })
}

$ yarn add -D jest-node-exports-resolver

// jest.config.js
module.exports = {
  //...
  resolver: 'jest-node-exports-resolver',
  // ...
}