Cannot add an object with observers to a Realm

I am new to SwiftUI and realm. I have created a Customer class as written below. I am trying to add some information to Realm database. My code is like this. And when I am trying to run it, I am getting error: "Cannot add an object with observers to a Realm."

Realm version is 10.28.6 SwiftUI 5 Xcode 13.4

import SwiftUI
import RealmSwift

class Customer: Object, ObjectKeyIdentifiable {

    @Persisted(primaryKey: true) var accountNumber = ""
    @Persisted var customerName = ""
    @Persisted var phoneNumber = ""
    @Persisted var address = ""
    @Persisted var city = ""
    @Persisted var state = ""
    @Persisted var zip = ""
}

//
//  ContentView.swift
//  ProjTests
//
// Realm 10.28.6

import SwiftUI
import RealmSwift

struct ContentView: View {

    @Environment(\.realm) var realm
    @Environment(\.dismiss) var dismiss

   @ObservedRealmObject var customer = Customer()
 //   @ObservedRealmObject var customer: Customer
    

    var body: some View {

        NavigationView {
            Form {
                Section {
                    VStack(alignment: .leading) {
                        Text("Customer Name")
                        TextField("Name", text: $customer.customerName)
                            .disableAutocorrection(true)
                            .textFieldStyle(RoundedBorderTextFieldStyle())
                    }
                }
                Section {
                    VStack(alignment: .leading){
                        Text("Phone Number")
                        TextField("10-digit Phone Number", text: $customer.phoneNumber)
                            .textFieldStyle(RoundedBorderTextFieldStyle())
                    }
                }
                Section {
                    VStack(alignment: .leading) {
                        Text("Address")
                        TextField("Address", text: $customer.address)
                        TextField("City", text: $customer.city)
                        TextField("State", text: $customer.state)
                        TextField("PIN Code", text: $customer.zip)
                    }
                }

                Section {
                    DatePicker("Date", selection: $customer.loanDate, displayedComponents: .date)
                }

                HStack() {
                    Button("Submit") {

                        customer.accountNumber = generateAccountNumber()

                        try? realm.write {
                          realm.add(customer)
                          }
                        }

                    }
                    .frame(width: 300, height: 15, alignment: .center)
            }

        .navigationTitle("Add New Customer")
        }
    }
}


extension ContentView {
    func generateAccountNumber() -> String {
        let newAccountNumber = Int.random(in: 10000000..<99999999)
        return(String(newAccountNumber))
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}

I will be very thankful for your help.