Javascript FindByIdAndUpdate在嵌套对象中创建_id

我正在开发一个接受基本邀请的端点，我需要通过参数(起诉Express)中提供的ID获得通知，然后更新他的result字段.接口/架构如下所示:

const NotiticationSchema = new Schema<Notitication>({
    title: { type: String, required: true },
    description: { type: String, default: null },
    date: { type: Date, default: Date.now() },
    type: { type: String, required: true },
    navigation: {
        type: String,
        enum: NotificationNav,
        required: true
    },
    navigationId: {
        type: String,
        enum: NotificationIds,
        required: true
    },
    teamId: { type: String, required: true },
    result: {
        type: {
            accepted: { type: Boolean, required: true },
            motivation: { type: String, required: true }
        },
        default: null
    }
});

这是我目前使用的代码:

const notification = await NotiticationModel.findByIdAndUpdate(req.params["id"]!, { $set: { result: { accepted: true, motivation: null } } });

预期输出应为:

{
  ...
  "result": {
    "accepted": true,
    "motivation": null
  }
}

NotiticationModel.findByIdAndUpdate()做什么:

{
  ...
  "result": {
    "accepted": true,
    "motivation": null,
    "_id": {
      "$oid": "65b23b495a60bda2c6e67996"
    }
  }
}

我从来没有遇到过这种行为，有谁能帮忙吗？

另外，我已经问过人工智能了，它没有给出任何有用的建议.