I am trying to make a full stack app where the MongoDB BSON document expires after a certain period of time. As you can see below, I put the expiry time at 4 minutes. However, the document gets deleted by 2:20 minutes. I have tried testing the expiry time at 2m, 3m. They are all expiring at within a span of 2:10-2:45 minutes. I am not sure why this is happening. What should I do to fix this?

const mongoose = require('mongoose')

const userSchema = new mongoose.Schema({
    note: {
        type: String,
        required: true,
    },
    completed:{
        type: Boolean
    },
    createdAt: { type: Date, expires: '4m', default: Date.now }
})

const User = mongoose.model('user', userSchema)

module.exports = User