load cell calibration with HX711

Question

I am trying to calibrate four 50kg Weight Sensors with Arduino's HX711 Amplifier AD Module. I am getting a variable range of errors. I am using this video as a reference link below. It shows me use a formula such as

Current Value= 0.8* Current value + 0.2* Sensor reading // which is taking an average of the senor

final value = ((Current Value-Actual Sensor Value) divided by reading of known weight multiplied by the known weight value

such as below,

known weight=100g

reading of known weight=2155

val = 0.8 * val + 0.2 *scale.read();

val_g=((val-159958)/2155.f*100);

The problem I am having is if I put the weight of 100 to the test the value, it keeps on changing up and down of the actual weight such as 103...101....100...102..100...97...99...103...102

I did try many attempts of calibrating but it always has that fluctuation in weight

My code:

//Oled Display
#include <SPI.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include "HX711.h"
#define WIRE Wire
Adafruit_SSD1306 display = Adafruit_SSD1306(128, 32, &WIRE);

//Weight
const int LOADCELL_DOUT_PIN = 3;
const int LOADCELL_SCK_PIN = 2;
const int Button_PIN = 5;

unsigned long timer ;


HX711 scale;

void setup() {
  //Weight
  Serial.begin(9600);
  scale.begin(LOADCELL_DOUT_PIN, LOADCELL_SCK_PIN);

  //For Display
  Serial.begin(9600);
  display.begin(SSD1306_SWITCHCAPVCC, 0x3C); // Address 0x3C for 128x32
  display.setTextSize(1.5);
  display.setTextColor(SSD1306_WHITE);

  while(1){
  display1();
  loop();
}
}
//Weight
long val=0;
float reads=0;
float val_g=0;
float val_gm=0;
float val_lb=0;
float zero;

void loop() {
  //val=scale.read();
  val = 0.8 * val + 0.2 *scale.read() ; //averaging
  val_g=((val-159958)/2155.f*100);
  //val_g=((val-166351)/2116.f*100);

 
pinMode(Button_PIN, INPUT_PULLUP);
   byte buttonState = digitalRead(Button_PIN);
  if (buttonState  == 0 && val_g>0|| val_g<0){
    zero=val_g;}
  
  
  val_gm=val_g - zero;
  val_lb= ((val_gm)*0.0022);
  
  Serial.print("Weight in G=");
  Serial.println(val_gm);
  
  Serial.println(val);

  
  Serial.print("Weight in Lb=");
  Serial.println(val_lb);
  }

void display1(){
  val_g;
  display.setCursor(10,0);
  display.print("Gram:");
  display.print(val_gm);
  display.setCursor(10,10);
  display.print("Pound:");
  display.print(val_lb);
  display.setCursor(6,6);
  display.display();
  display.clearDisplay();  
  }

Load Cell calibration for reference