Float subtracting in increments of 1 no matter what value it's subtracted by

I'm currently trying to implement movement deceleration on my first person controller, and I am doing that by subtracting the movement speed by a certain deceleration value every frame after the player stops moving. The system is working, however according to the debug console the decelerationSpeed variable is being subtracted by 1 every frame instead of whatever number I declare decelerationRate as.

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class PlayerMovementScript : MonoBehaviour
 {
     public CharacterController controller;
 
     public float speed = 12f;
     public float decelerationSpeed;
 
     public float gravity = -9.81f;
     public float jumpHeight = 3f;
 
     private float previousY;
     public float nextTimeToCheckY;
     public float bounceTime = 8;
 
     public float decelerationRate = 0.5f;
 
     public Transform GroundCheck;
     public float groundDistance = 0.4f;
     public LayerMask groundMask;
 
     public float MovementDampening = 0.25f;
 
     public float decelerationDistance = 0.15f;
 
     public float previousX;
     public float previousZ;
 
     Vector3 velocity;
 
     Vector3 previousMove;
 
     Vector3 previousPosition;
 
     bool isGrounded;
 
     bool decelerating = false;
 
     private void Start()
     {
         decelerationSpeed = speed;
     }
 
     // Update is called once per frame
     void Update()
     {
         isGrounded = Physics.CheckSphere(GroundCheck.position, groundDistance, groundMask);
         Debug.Log("isGrounded is " + isGrounded);
 
         if(isGrounded && velocity.y < 0)
         {
             velocity.y = -1f;
         }
 
         float x = Input.GetAxisRaw("Horizontal");
         float z = Input.GetAxisRaw("Vertical");
 
         if (x != 0 || z != 0)
         {
             decelerationSpeed = speed;
             decelerating = false;
         }
 
         Vector3 move = transform.right * x + transform.forward * z;
         move.Normalize();
 
         if (isGrounded)
         {
             if (x != 0 || z != 0)
             {
                 controller.Move(move * speed * Time.deltaTime);
                 previousMove = move;
             }
             else if (x == 0 && z == 0 && (previousZ != 0 || previousX != 0))
             {
                     controller.Move(previousMove * decelerationSpeed * Time.deltaTime);
                     decelerationSpeed = decelerationSpeed - decelerationRate;
                     decelerating = true;
                     if (decelerationSpeed == 0)
                 {
                     decelerationSpeed = speed;
                     decelerating = false;
                 }
             }
         }
         else if (!isGrounded)
         {
             if ((x == 0 && z == 0) || Vector3.Dot(move, previousMove) < 0)
             {
                 controller.Move(previousMove * speed * Time.deltaTime);
             }
             else {
                 Vector3 newMove = previousMove + move;
                 newMove.Normalize();
                 controller.Move(newMove * speed * Time.deltaTime);
             }
         }
 
 
 
         previousY = transform.position.y;
 
         if (Input.GetButtonDown("Jump") && isGrounded) {
 
             previousMove = move;
             
             velocity.y = Mathf.Sqrt(jumpHeight * -2f * gravity);
         }
 
         velocity.y += gravity * Time.deltaTime;
 
         controller.Move(velocity * Time.deltaTime);
         
         if (velocity.y != 0 && previousY == transform.position.y && Time.time >= nextTimeToCheckY)
         {
             nextTimeToCheckY = Time.time + 1f / bounceTime;
             velocity.y = 0;
         }
         if (!decelerating)
         {
             previousX = x;
             previousZ = z;
         }
     }
 }