Unity simple & fast light flicker script

LightFlickerEffect.cs

using UnityEngine;
using System.Collections.Generic;

// Written by Steve Streeting 2017
// License: CC0 Public Domain http://creativecommons.org/publicdomain/zero/1.0/

/// <summary>
/// Component which will flicker a linked light while active by changing its
/// intensity between the min and max values given. The flickering can be
/// sharp or smoothed depending on the value of the smoothing parameter.
///
/// Just activate / deactivate this component as usual to pause / resume flicker
/// </summary>
public class LightFlickerEffect : MonoBehaviour {
    [Tooltip("External light to flicker; you can leave this null if you attach script to a light")]
    public new Light light;
    [Tooltip("Minimum random light intensity")]
    public float minIntensity = 0f;
    [Tooltip("Maximum random light intensity")]
    public float maxIntensity = 1f;
    [Tooltip("How much to smooth out the randomness; lower values = sparks, higher = lantern")]
    [Range(1, 50)]
    public int smoothing = 5;

    // Continuous average calculation via FIFO queue
    // Saves us iterating every time we update, we just change by the delta
    Queue<float> smoothQueue;
    float lastSum = 0;


    /// <summary>
    /// Reset the randomness and start again. You usually don't need to call
    /// this, deactivating/reactivating is usually fine but if you want a strict
    /// restart you can do.
    /// </summary>
    public void Reset() {
        smoothQueue.Clear();
        lastSum = 0;
    }

    void Start() {
         smoothQueue = new Queue<float>(smoothing);
         // External or internal light?
         if (light == null) {
            light = GetComponent<Light>();
         }
    }

    void Update() {
        if (light == null)
            return;

        // pop off an item if too big
        while (smoothQueue.Count >= smoothing) {
            lastSum -= smoothQueue.Dequeue();
        }

        // Generate random new item, calculate new average
        float newVal = Random.Range(minIntensity, maxIntensity);
        smoothQueue.Enqueue(newVal);
        lastSum += newVal;

        // Calculate new smoothed average
        light.intensity = lastSum / (float)smoothQueue.Count;
    }

}

It's not that bad. It's straightforward and gives an idea on a dissipating light. It does cause some garbage. Time.deltaTime is not a big deal in his use because he is yield return null, which is equal to waiting for the next Update() call.
There's no reason to hate on it so much??

Hey @stadoblech, thanks a lot for your feedback, I'll take all that into account for future scripting.

About the magic numbers, it was a short quick script, so it was just making it simple to read first sight, I usually prefer that.

About the lighting intensity, I adjusted it for my scene to look as I wanted, that's also why the Magic numbers, just change them according to your scene/pipeline, expose in editor, etc.

And regarding the delta time in coroutine, I would like you to further explain why is that a really bad idea, cause I've used that a lot and I'm really interested on knowing why is that bad. How would you increment the timer "t" inside the while of a coroutine?

Thanks!

I diсided do like this.

 public class FlickeringLight : MonoBehaviour
    {
        [Header("References")]
        [Tooltip("Light Source")]
        [SerializeField] private Light _light;
        [Tooltip("Emission renderer")]
        [SerializeField] private Renderer _renderer;
        [Tooltip("Material index if mesh have more then 1 material")]
        [SerializeField] private int _materialIndex = 0;
        [Space(3f)]
        [Header("Options")]
        [Tooltip("How much to smooth out the randomness; lower values = sparks, higher = lantern")]
        [Range(1, 50)]
        [SerializeField] private int _smoothing = 5;
        [Range(0, 50)]
        [Tooltip("Delay between iterations")]
        [SerializeField] private int _delay = 5;
        [Tooltip("Duration of iterations")]
        [SerializeField] private float _duration = 5;
        
        
        private float _maxIntensity;
        private float _minIntensity = 0;
        private Queue<float> _smoothQueue;
        private float _lastSum = 0;
        private float _colorIntensity;
        private Color _color;
        private float _factor;
        private Coroutine _flickCoroutine;
        private WaitForSeconds _seconds;
        public void Reset()
        {
            StopCoroutine(_flickCoroutine);
            _smoothQueue.Clear();
            _lastSum = 0;
        }
        private void Start()
        {
            _seconds = new WaitForSeconds(_delay);
            _color = _renderer.materials[_materialIndex].GetColor("_EmissionColor");
            _colorIntensity = (_color.r + _color.g + _color.b) / 3f;
            _maxIntensity = _light.intensity;
            _smoothQueue = new Queue<float>(_smoothing);
            _flickCoroutine = StartCoroutine(Flick());
        }

        private void DoFlick()
        {
            if (_light == null)
                return;

            // pop off an item if too big
            while (_smoothQueue.Count >= _smoothing)
            {
                _lastSum -= _smoothQueue.Dequeue();
            }

            // Generate random new item, calculate new average
            float newVal = Random.Range(_minIntensity, _maxIntensity);
            _smoothQueue.Enqueue(newVal);
            _lastSum += newVal;

            // Calculate new smoothed average
            _light.intensity = _lastSum / (float)_smoothQueue.Count;
            _factor = _light.intensity / _colorIntensity;
            _renderer.sharedMaterials[_materialIndex].SetColor("_EmissionColor",new Color(_color.r*_factor,_color.g*_factor,_color.b*_factor));
        }

        private IEnumerator Flick()
        {
            float t = 0.0f;
            yield return _seconds;
            while (t<_duration)
            {
                DoFlick();
                t += Time.deltaTime;
                yield return null;
            }
            _flickCoroutine  = StartCoroutine(Flick());
        }

Movie.003-1.mp4

Forked for 2D URP :)