The problem of failed verification by using graphic CAPTCHA when registering in vue

use axios for registration, use graphic verification code to verify whether it is correct, cannot be verified correctly,
1. Get the graphic verification code first


this.$http({
        method: "get",
        url: this.api + "/app/platform/getImgCodeUrl", 
        withCredentials: true
      }).then((data) => {
        if(data.data && data.data.code === "200"){
          this.imgCode = data.data.databody.imgCodeUrl + "?" + new Date()
        }
        this.$store.commit("changeLoading", false)
      })

the image address is returned, which is not under the same domain name as the background address I requested.

Click to submit for registration. The backend needs partner seessionid to determine whether the request is from the same device.

The request sessionid of

picture is different from the registered sessionid. How to solve this problem