Weird object rotation even with rotation constraints frozen

I have a game in a 3D world space. The gameplay is in 2D. So, the player has position frozen on 1 axis and rotation frozen on 2 axes. Position freeze works fine. However, some of the players experience unwanted object rotation during the gameplay even with frozen constraints (I have never encountered such an issue during BETA-test)

Object unwanted weird rotation

Constraints while I test it for myself:

My code (Player movement)

 public class Movement : MonoBehaviour
 {
     public Rigidbody rb;
     public int clickForce = 500;
     private Plane plane = new Plane(Vector3.up, Vector3.zero);
     public float speed;
     public Slider staminaBar;
 
     private void Start()
     {
         Rigidbody rb = GetComponent<Rigidbody>();
         rb.centerOfMass = Vector3.zero;
         rb.inertiaTensorRotation = Quaternion.identity;
     }
 
     void FixedUpdate()
     {
         Cursor.visible = false;
         Cursor.lockState = CursorLockMode.Confined;
 
         if (Input.GetMouseButton(0))
         {
             if (staminaBar.value > 0.25)
             {
                 var ray = Camera.main.ScreenPointToRay(Input.mousePosition);
 
                 float enter;
 
                 if (plane.Raycast(ray, out enter))
                 {
                     var hitPoint = ray.GetPoint(enter);
                     var mouseDir = hitPoint - gameObject.transform.position;
                     mouseDir = mouseDir.normalized;
                     rb.AddForce(mouseDir * clickForce);
                 }
 
                 Plane playerPlane = new Plane(Vector3.up, transform.position);
                 Ray rayy = Camera.main.ScreenPointToRay(Input.mousePosition);
                 float hitdist = 0.0f;
 
                 if (playerPlane.Raycast(rayy, out hitdist))
                 {
                 Vector3 targetPoint = rayy.GetPoint(hitdist);
                 Quaternion targetRotation = Quaternion.LookRotation(targetPoint - transform.position);
                 transform.rotation = Quaternion.Slerp(transform.rotation, targetRotation, speed * Time.deltaTime);
                 }
             }
         }
     }
 }