I am getting duplicate key error on mongoose. I deleted .next folder form root and updated my mongoose schema but still I am getting this error :

MongoServerError: E11000 duplicate key error collection: restaurant.products index: id_1 dup key: { id: null }

My product schema :
Previously I had an id field by mistake and i deleted it but still :

import { Schema, model, models } from "mongoose";

const productSchema = new Schema({
  title: {
    type: String,
    required: true,
  },
  category: {
    type: String,
    required: true,
  },
  images: {
    type: [String],
    required: true,
  },
  price: {
    type: Number,
    required: true,
  },
  rating: {
    type: Number,
    default: () => Math.floor(Math.random() * 4) + 2, // Generates random number between 2 and 5
    required: true,
  },
  description: {
    type: String,
    required: true,
  },
});

const Product = models.Product || model("Product", productSchema);

export default Product;

Here is my server action :

"use server";
import { connectdb } from "@/config/db";
import Product from "../model/Product";
import { revalidatePath } from "next/cache";

export const addProduct = async (product: any) => {
  try {
    await connectdb();
    const { title, description, price, category, images } = product;
    const newProduct = new Product({
      title,
      description,
      price,
      category,
      images,
    });
    const saved = await newProduct.save();
    console.log("SAVED PRODUCT:", saved);
    revalidatePath("/admin/products");
    revalidatePath("/menu");
    return { success: true, message: "Added product successfully !!" };
  } catch (err) {
    console.log(err);
    return { success: false, message: "Internal server error" };
  }
};