(UNITY 2D) How do I flip a sprite based on parent's rotation?

Question

I have a thing set up, that makes the gun rotate in the direction of the cursor around the player and I want to make it so, when it's past or below a certain rotation.z value, it flips the gun's sprite. This is the code I have:

 using UnityEngine;

public class Shooting : MonoBehaviour {

 private Camera _mainCam;
 private Vector3 _mousePos;
 public SpriteRenderer gun;
 public GameObject thisObj;

 private void Start()
 {
     _mainCam = GameObject.Find("Main Camera").GetComponent<Camera>();
 }

 private void Update()
 {
     RotatePoint();
     RotateGun();
 }

 void RotateGun()
 {
     if (thisObj.transform.localEulerAngles.z is < 270f or > 90f)
     {
         gun.flipY = true;
     }
     else if(thisObj.transform.localEulerAngles.z is > 270f or < 90f)
     {
         gun.flipY = false;
     }
     Debug.Log(thisObj.transform.localEulerAngles.z);
 }
 void RotatePoint()
 {
     _mousePos = _mainCam.ScreenToWorldPoint(Input.mousePosition);
     Vector3 rotation = _mousePos - transform.position;
     float rotZ = Mathf.Atan2(rotation.y, rotation.x) * Mathf.Rad2Deg;
     transform.rotation = Quaternion.Euler(0,0,rotZ);
 }

}

And here's my hierarchy:

Any help is appreciated, I have no idea why it's not working... I've tried thisObj.transform.rotation.z too, without any success.