Problem with crouching

Hi :D,

so basically I am new to unity and I am trying to learn to add new mechanics. I am creating a 3D game let's say FPS style. I am following guides on youtube and I managed to make my character move and jump. However, after I added simple code to make my character crouch it appears that it starts to sink a little bit into the floor. I am changing the height of the CharacterController to achieve crouching but after I hit shift to make my character crouch it just sinks even more into the ground and not changing its actual height.

I could leave it like that since it makes an illusion of crouching but I would love to know where I made a mistake. Also because of that when my character is falling down it slows down before hitting the floor which is annoying.

Here is my code:

 public class PlayerMovement : MonoBehaviour
 {
     public CharacterController controller;
     public float speed = 12f;
     public float jumpHeight = 3f; 
 
     Vector3 velocity;
     public float gravity  = -30f;
 
     public Transform groundCheck;
     public float groundDistance = 0.4f; 
     public LayerMask groundMask;
 
     bool isGrounded;
 
     // Start is called before the first frame update
     void Start()
     {
         controller = gameObject.GetComponent<CharacterController>();
     }
 
     // Update is called once per frame
     void Update()
     {
         isGrounded = Physics.CheckSphere(groundCheck.position, groundDistance, groundMask);
 
         if (isGrounded && velocity.y < 0)
         {
             velocity.y = -2;
         }
         float x = Input.GetAxis("Horizontal");
         float z = Input.GetAxis("Vertical");
 
         Vector3 move = transform.right * x + transform.forward * z;
 
         controller.Move(move  * speed * Time.deltaTime);
 
         if(Input.GetButtonDown("Jump") && isGrounded)
         {
             velocity.y = Mathf.Sqrt(jumpHeight * -2f * gravity);
         }
 
         
 
         velocity.y += gravity * Time.deltaTime;
 
         controller.Move(velocity * Time.deltaTime);
         
         if (Input.GetKey(KeyCode.LeftShift)) 
         {
             controller.height = 0.5f;
             speed = 6f;
         }
         else
         {
             controller.height = 2.8f;
             speed = 12f;
         }
         
     }
 }

Also as a side question. Sometimes when I change values inside the script it doesn't seem to change it inside the unity inspector. For example, I changed public float groundDistance = 0.4f; into 0.2f, and after saving in inspector it still was 0.4f.

Yeah, it's probably something obvious but I will gladly hear your advice.

cheers!