unity3D 2个触发器交界处会变速，怎么解决？

Question

上面的方块移动到交界处会变速，然后有回归正常速度，怎么解决，求解
脚本

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class bsTest : MonoBehaviour
{
    public GameObject endpointPosition;
    int speed = 2;
    // Start is called before the first frame update
    void Start()
    {
        
    }

    // Update is called once per frame
    void Update()
    {
        
    }

    private void OnTriggerStay(Collider other)
    {
        if (transform.position.z < endpointPosition.transform.position.z) { 
            Debug.Log(speed);
        }
        transform.position = Vector3.MoveTowards(transform.position, endpointPosition.transform.position, speed * Time.deltaTime);
    }
}