多层数据对象深拷贝的问题

贴代码，为什么我自己写的这个递归最后改变原数据的值，被拷贝的数据也会改变（没变成深拷贝）

    const deepCopy = (instance) => {
      const result = Array.isArray(instance) ? [] : instance instanceof Object ? {} : null
      if (result === null) {
        throw new Error(`需要传入Array或Object类型的参数，但现在是${typeof instance}类型的参数`)
      }
      if (Array.isArray(instance)) {
        for (let i = 0; i < instance.length; i++) {
          const inst = instance[i]
          result[i] = inst
          if (inst instanceof Object) {
            deepCopy(inst)
          }
        }
      } else if (instance instanceof Object) {
        for (const key in instance) {
          result[key] = instance[key]
          if (Array.isArray(instance[key]) || instance[key] instanceof Object) {
            deepCopy(instance[key])
          }
        }
      }
      return result
    }

    const o = JSON.parse('{"hnzhghActivity":{"activityType":"4","activityTitle":"测试","startTime":"2022-09-01 00:00:00","endTime":"2022-10-25 00:00:00","imgId":"282203357600632832","imgPath":"https://le/2022/09/02/bae50aff-28a3-487a-b99c-1fec2c7ad761.png","createUser":"258054318004981760","unionId":"248601951852867584","unionName":"河南省总工会","createUserName":"lvyuhui"},"answerRule":"阿瓦达瓦方法","answerNum":5,"answerTime":30,"answerFrequency":1,"correctNumber":1,"hnzhghActivityAnswerAwardList":[{"awardType":"2","awardName":"谢谢参与","awardImg":"htile/picture/else.png"},{"awardType":"1","awardName":"23","awardTotal":"23","awardImg":"https://ghile/2022/09/02/1af9e8ae-447e-4ddf-a3b9-6b2839c3209f.png","awardImgId":"282203439435698176","awardProbability":"23","deliveryType":"1"},{"awardType":"1","awardName":"23","awardTotal":"232","awardImg":"https://gile/2022/09/02/49be25a5-e2a1-4a74-a3c8-497f9d327a30.png","awardImgId":"282203467839524864","awardProbability":"3","deliveryType":"2","address":"发回给你跟儿童边呢人"}],"hnzhghActivityAnswerTopicList":[{"topicId":"275063568107655168","topicName":"《工会法》竞赛题库0813"},{"topicId":"273491974549753856","topicName":"809题库测试845"},{"topicId":"271339739891978240","topicName":"测试专用题库"}],"topicName":"《工会法》竞赛题库0813，809题库测试845，测试专用题库"}')
    console.log(o);
    console.log(deepCopy(o));

可以尝试改变递归后返回的数据，能改变原数据