Even though I have defined other models same as Todo.
Unable to fix the issue.

I am creating newTodo inside helper.js which is getting called from client component - BookForm.ts

import mongoose from "mongoose";

const TodoSchema = new mongoose.Schema(
  {
    title: {
      type: String,
      required: true,
      minLength: 5,
    },
    userId: {
      type: mongoose.Schema.Types.ObjectId,
    },
  },
  { timestamps: true }
);

export default mongoose.models.Todo || mongoose.model("Todo", TodoSchema);

// inside helper.ts

export const saveTodo = async (title: any, email: any) => {
  const userId = await User.findOne({ email: email });
  const newTodo = new Todo({ title, userId: userId._id });
  await newTodo.save();
};