Player moves forward when switching camera view?

I'm relatively new to coding and unity, so apologies if this is a newbie question...
I'm trying to make a character controller that can switch between first and third person view. The controls for each are slightly different: First person always faces the camera direction and strafes left/right and walks backwards with wasd, but in third person the character can move in directions independently from camera direction. The issue is that when a camera switch is triggered the player object moves forward by a fraction of a unit. If I don't press any directional keys but just trigger the camera switch I can move them across the map, hilariously. I don't know what's causing this, and have included my cam switch and my character controller below.

Code (CSharp):

1. using UnityEngine;
2.  
3. public class CamSwitch : MonoBehaviour
4. {
5.     public Camera FPCam;
6.     public Camera TPCam;
7.  
8.     public bool fpCam = true;
9.  
10.     // Start is called before the first frame update
11.     void Start()
12.     {
13.         FPCam.enabled = fpCam;
14.         TPCam.enabled = !fpCam;
15.     }
16.  
17.     // Update is called once per frame
18.     void Update()
19.     {
20.         if(Input.GetKeyDown(KeyCode.C))
21.         {
22.             fpCam = !fpCam;
23.             FPCam.enabled = fpCam;
24.             TPCam.enabled = !fpCam;
25.         }
26.     }
27. }
28.  

Code (CSharp):

1. using UnityEngine;
2.  
3. public class PlayerMovement : MonoBehaviour
4. {
5.     public CharacterController controller;
6.     public Camera FPcam, TPcam;
7.     Transform camT;
8.  
9.     public float walkSpeed = 4f;
10.     public float runSpeed = 8f;
11.     public float gravity = -20f;
12.     public float jumpHeight = 2f;
13.  
14.     public Transform groundCheck;
15.     public float groundDistance = 0.4f;
16.     public LayerMask groundMask;
17.  
18.     Vector3 velocity;
19.     bool isGrounded;
20.    
21.     //useful for animation transitions
22.     public float speedSmoothTime = 0.1f;
23.     float speedSmoothVelocity;
24.     float currentSpeed;
25.  
26.     //smooths character turning when using camera or wasd
27.     public float turnSmoothTime = 0.2f;
28.     float turnSmoothVelocity;
29.  
30.     void Start()
31.     {
32.         camT = TPcam.transform;
33.     }
34.     // Update is called once per frame
35.     void Update()
36.     {
37.         GroundCheck();
38.  
39.         //looks for wasd key input to move
40.         float x = Input.GetAxis("Horizontal");
41.         float z = Input.GetAxis("Vertical");
42.  
43.         if (FPcam.isActiveAndEnabled) //if in first person view, use these controls
44.         {
45.             FirstPersonControls(x, z);              
46.         }
47.         else //if (TPcam.isActiveAndEnabled)
48.         {
49.             ThirdPersonControls(x, z);
50.         }
51.  
52.         if (Input.GetButtonDown("Jump"))
53.         {
54.             Jump();
55.         }
56.  
57.         CalcGravity();
58.     }
59.  
60.     void FirstPersonControls(float x, float z)
61.     {
62.         //if the character is running, change speed and smooth movement
63.         bool running = Input.GetKey(KeyCode.LeftShift);
64.         float targetSpeed = ((running) ? runSpeed : walkSpeed);
65.         currentSpeed = Mathf.SmoothDamp(currentSpeed, targetSpeed, ref speedSmoothVelocity, speedSmoothTime);
66.  
67.         //moves player controller based on above inputs
68.         Vector3 move = transform.right * x + transform.forward * z;
69.         controller.Move(move * currentSpeed * Time.deltaTime);
70.     }
71.  
72.     void ThirdPersonControls(float x, float z)
73.     {
74.         //prevents camera direction from being reset every time rotation stops
75.         Vector2 input = new Vector2(x, z);
76.         Vector2 inputDir = input.normalized;
77.  
78.         if (inputDir != Vector2.zero)
79.         {
80.             //will move player in the direction that the camera is facing
81.             float targetRotation = Mathf.Atan2(x, z) * Mathf.Rad2Deg + camT.eulerAngles.y;
82.             transform.eulerAngles = Vector3.up * Mathf.SmoothDampAngle(transform.eulerAngles.y, targetRotation, ref turnSmoothVelocity, turnSmoothTime);
83.         }
84.  
85.         //if the character is running, change speed and smooth movement
86.         bool running = Input.GetKey(KeyCode.LeftShift);
87.         //multiplying by inputDir.magnitude prevents movement when not actively using wasd
88.         float targetSpeed = ((running) ? runSpeed : walkSpeed) * inputDir.magnitude;
89.         currentSpeed = Mathf.SmoothDamp(currentSpeed, targetSpeed, ref speedSmoothVelocity, speedSmoothTime);
90.  
91.         controller.Move(transform.forward * currentSpeed * Time.deltaTime);
92.     }
93.  
94.     void GroundCheck()
95.     {
96.         //checks if the groundcheck object at the players feet is touching an object with the layer "ground", will set bool accordingly
97.         isGrounded = Physics.CheckSphere(groundCheck.position, groundDistance, groundMask);
98.         if (isGrounded && velocity.y < 0) //makes sure player sticks to the ground
99.         {
100.             velocity.y = -2f;
101.         }
102.     }
103.  
104.     void Jump()
105.     {
106.         if (isGrounded)
107.         {
108.             Debug.Log("Jumping");
109.             velocity.y = Mathf.Sqrt(jumpHeight * -2f * gravity);
110.         }
111.  
112.     }
113.  
114.     void CalcGravity()
115.     {
116.         //gravity calculations
117.         velocity.y += gravity * Time.deltaTime;
118.         controller.Move(velocity * Time.deltaTime);
119.     }
120. }

 

It might be floating point error, perhaps caused by setting the .eulerAngles every frame (line 82), then the new position/rotation offset triggers your physics and you creep a bit?