Pedometer algorithm doesn't count steps properly using accelerometer data

Question

I am using react-native and I want to count the steps of the user like Samsung Health step indicator.

I am using react-native-sensors library to access accelerometer data.

I followed this tutorial for pedometer algorithm, implemented in react-native.

import {View, Text} from 'react-native';
import {
  accelerometer,
  SensorTypes,
  setUpdateIntervalForType,
} from 'react-native-sensors';

setUpdateIntervalForType(SensorTypes.accelerometer, 400);

const App = () => {
  const [xAcceleration, setXAcceleration] = useState(0);
  const [yAcceleration, setYAcceleration] = useState(0);
  const [zAcceleration, setZAcceleration] = useState(0);
  const [magnitudePrevious, setMagnitudePrevious] = useState(0);
  const [steps, setSteps] = useState(0);

  useEffect(() => {
    const subscription = accelerometer
      .pipe(data => data)
      .subscribe(speed => {
        setXAcceleration(speed.x);
        setYAcceleration(speed.y);
        setZAcceleration(speed.z);
      });

    return () => {
      subscription.unsubscribe();
    };
  }, []);

  useEffect(() => {
    const magnitude = Math.sqrt(
      Math.pow(xAcceleration, 2) +
        Math.pow(yAcceleration, 2) +
        Math.pow(zAcceleration, 2),
    );

    const magnitudeDelta = magnitude - magnitudePrevious;

    setMagnitudePrevious(() => magnitude);

    // I tried magnitudeDelta > 6, magnitudeDelta > 4, 
    // magnitudeDelta > 2, magnitudeDelta > 10 but didn't work properly
    if (magnitudeDelta > 2) setSteps(prevSteps => prevSteps + 1);
  }, [xAcceleration, yAcceleration, zAcceleration]);

  return (
    <View>
      <Text>{steps}</Text>
    </View>
  )
}

If a shake my phone upwards or sideways it increments the steps but I think it's ok because samething happens in Samsung Health. But the main problem is it is not as accurate as Samsung Health when you walk.

For example: If a stepped 20 times it only counts 8 of them. I want it to be close to actual value.