LeanTween does a stuttery animation while rotating to 180/-180 degrees

Question

So I'm trying to make LeanTween rotate an object to 180/-180 degrees but it makes a stuttery animation while doing so.

Stuttery Rotation

Here's my code:

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

public class RotateScript360 : MonoBehaviour
{
    public GameObject level;
    public AudioSource audioSource;
    public AudioClip rotateSound;
    private int rotation;
    private bool cooldown;

    // Start is called before the first frame update
    void Start()
    {
        
    }

    // Update is called once per frame
    void Update()
    {
        IEnumerator cooldownEnd()
        {
            yield return new WaitForSeconds(1);
            cooldown = false;
        }

        if (cooldown == false)
        {
            if ((Input.GetKeyDown("x")) || (Input.GetButton("X")))
            {
                if(rotation != -180)
                {
                    audioSource.PlayOneShot(rotateSound);
                    rotation = rotation - 90;
                    LeanTween.rotateX(level, rotation, 1).setEaseOutExpo();
                    cooldown = true;
                    StartCoroutine(cooldownEnd());
                }
            }

            if ((Input.GetKeyDown("z")) || (Input.GetButton("Z")))
            {   
                if (rotation != 180)
                {
                    audioSource.PlayOneShot(rotateSound);
                    rotation = rotation + 90;
                    LeanTween.rotateX(level, rotation, 1).setEaseOutExpo();
                    cooldown = true;
                    StartCoroutine(cooldownEnd());
                }
            }
        }
    }
}

What should I do?

Sorry if my English is bad.

I tried to make int rotation value a little bit lower, cause I was thinking it would make the stutter go away by making LeanTween rotating on 1 side (it would be 178, not 180). But I've gotten the same results.