I'm trying to make simple sign-in function for my web using firebase however I'm getting an error saying: ERROR db._checkNotDeleted is not a function

my Firebase versions is 9 and React is running on 17.0.2.

This is my firebase config file snippet (Will hide configurations since its unnecessary):

import { initializeApp } from "firebase/app";
import { getAuth, signInWithPopup, GoogleAuthProvider } from "firebase/auth";
import { getDatabase, ref, set } from "firebase/database";
import { getFirestore, doc, getDoc, collection, addDoc, getDocs, query, where} from "firebase/firestore";



const firebaseConfig = {
  */*/*/*/
};

const app = initializeApp(firebaseConfig);


export const auth = getAuth(app);

  export const createUserProfileDocument = async (userAuth, additionalData) => {
    if(!userAuth) return;

    const docRef = doc(db, "users", `${userAuth.uid}`);
    
    const docSnap = await getDoc(docRef);

    if (!docSnap.exists()) {
      const { displayName, email } = userAuth;
      const createdAt = new Date();
    
     
      try {
        await set(ref(db, 'users/' + `${userAuth.uid}`), {
          displayName: "TEST"
        })
        console.log("HERE");
       
      } catch (error) {
        console.log("ERROR", error.message);
      }
    }
    return docRef;
  }

  
  

  const provider = new GoogleAuthProvider();

  export const signInWithGoogle = () => {
      signInWithPopup(auth, provider)
      .then((result) => {
            console.log(result);
      }).catch((error) => {
          console.log(error);
      })
  }
 
  
  
  const db = getFirestore();

Here is my project: https://github.com/poolpy111/oto-clothing/tree/master/src

In debugger error line appears on line 43 which is where I use firebase's "ref" method. What I'm supposed to do?