Rotation reversing for a single frame while turning.

I'm moving my player character using the following code:

            public class PlayerController : MonoBehaviour
            {
             //Components
             [SerializeField] Camera gameCamera;
             [SerializeField] Rigidbody playerbody;
         
             //Physics Constants
             private float acc = 0.0703125f;
             private float frc = 0.0703125f;
             private float top = 9f;
         
         
              //Inputs
             public Vector3 moveInput;
             public Vector3 localizedInput;
             
              //Coroutines
             Coroutine turnCoRt;
         
         
             //On Move is called when activity from the Move InputAction is detected.
             public void OnMove(InputValue value)
             {
                 Vector2 rawInput = value.Get<Vector2>();
                 moveInput = new Vector3(rawInput.x, 0, rawInput.y);
         
                 if (moveInput != Vector3.zero)
                 {
                     //Get direction of input relative to the camera direction.
                     localizedInput = GetLocalizedInput();
                     if (turnCoRt != null) StopCoroutine(turnCoRt);
                     turnCoRt = StartCoroutine(Turn());
                 }
                 else
                 {
                     //Get direction of input relative to the camera direction.
                     localizedInput = Vector3.zero;
                     if (turnCoRt != null) StopCoroutine(turnCoRt);
                 }
             }
         
         
             //Update is called once per frame.
             private void Update()
             {
                 localizedInput = GetLocalizedInput();
             }
         
             // FixedUpdate is called once per fixed timestep frame.
             void FixedUpdate()
             {
                 if (moveInput != Vector3.zero)
                 {
                    Accelerate(acc);
                 }
                 else
                 {
                    Decelerate(frc);
                 }
              }
         
         void Accelerate(float acc)
             {
                 if (playerbody.velocity.magnitude < top)
                 {
                     if (playerbody.velocity.magnitude + acc < top)
                     {
                         playerbody.AddForce(acc * localizedInput, 
                         ForceMode.VelocityChange);
                     }
                     else
                     {
                         playerbody.AddForce((top - playerbody.velocity.magnitude) * 
                         localizedInput, ForceMode.VelocityChange);
                     }
                 }
             }
         
             void Decelerate(float dec)
             {
                 if (playerbody.velocity.magnitude > 0)
                 {
                     if (dec < playerbody.velocity.magnitude)
                     {
                         playerbody.AddForce(dec *
                         -playerbody.velocity.normalized, 
                         ForceMode.VelocityChange);
                     }
                     else
                     {
                         playerbody.velocity = Vector3.zero;
                     }
                 }
             }
         
             Vector3 GetLocalizedInput ()
             {
                 Vector3 camVector = 
                 Vector3.ProjectOnPlane(gameCamera.transform.forward,
     
                 transform.up).normalized;
                 
                Quaternion camRotation = 
                Quaternion.FromToRotation(Vector3.forward, camVector);
                
                Vector3 result = camRotation * moveInput;
                
                return result;
             }
         
             IEnumerator Turn ()
             {
                 for (float r = 0; r < 1; r += Time.deltaTime)
                 {
                     if (r > 1) r = 1; 
         
                     transform.rotation = Quaternion.Slerp(Quaternion.LookRotation
     
                     (transform.forward, transform.up), Quaternion.LookRotation
     
                     (localizedInput, transform.up), r);
         
                     playerbody.velocity = transform.forward * 
                     playerbody.velocity.magnitude;
                     
                     yield return null;
                 }
         
                 for (; ; )
                 {
                     transform.rotation = Quaternion.LookRotation(localizedInput,
     
                     transform.up);
         
                     playerbody.velocity = transform.forward * 
                     playerbody.velocity.magnitude;
         
                     yield return null;
                 }
             }
         }

This works for the most part but sometimes when holding left or right the rotation of the player character is reversed 180 degrees around the Y axis for a single frame. Can anybody help me figure out what is causing it?