Underwater effect not working as expected in Unity

Question

I have imported an underwater effect shader from the following youtube video: https://www.youtube.com/watch?v=GweaV8ZO7oA

However, the following errors show up at the console. I assume this is because of the version difference of the unity editor. I have tried to get an understanding of the errors for the past days but couldn't find anything.

here is the shader script:

using System;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Rendering;
using UnityEngine.Rendering.Universal;

public class Underwater : ScriptableRendererFeature
{
    [System.Serializable]
    public class Settings
    {
        //future settings
        public Material material;
        public RenderPassEvent renderPassEvent = RenderPassEvent.AfterRenderingSkybox;
        public Color color;
        public float distance = 10;
        [Range(0, 1)]
        public float alpha;
        public float refraction = 0.1f;
        public Texture normalmap;
        public Vector4 UV = new Vector4(1,1,0.2f,0.1f);
    }

    public Settings settings = new Settings();
    class Pass : ScriptableRenderPass
    {
        public Settings settings;
        private RenderTargetIdentifier source;
        RenderTargetHandle tempTexture;

        private string profilerTag;

        public void Setup(RenderTargetIdentifier source)
        {
            this.source = source;
        }

        public Pass(string profilerTag)
        {
            this.profilerTag = profilerTag;
        }

        public override void Configure(CommandBuffer cmd, RenderTextureDescriptor cameraTextureDescriptor)
        {
            cmd.GetTemporaryRT(tempTexture.id, cameraTextureDescriptor);
            ConfigureTarget(tempTexture.Identifier());
            ConfigureClear(ClearFlag.All, Color.black);
        }

        public override void Execute(ScriptableRenderContext context, ref RenderingData renderingData)
        {
            CommandBuffer cmd = CommandBufferPool.Get(profilerTag);
            cmd.Clear();

            //it is very important that if something fails our code still calls 
            //CommandBufferPool.Release(cmd) or we will have a HUGE memory leak
            try
            {
                //here we set out material properties
                //...
                settings.material.SetFloat("_dis", settings.distance);

                settings.material.SetFloat("_alpha", settings.alpha);

                settings.material.SetColor("_color", settings.color);

                settings.material.SetTexture("_NormalMap", settings.normalmap);

                settings.material.SetFloat("_refraction", settings.refraction);

                settings.material.SetVector("_normalUV", settings.UV);

                //never use a Blit from source to source, as it only works with MSAA
                // enabled and the scene view doesnt have MSAA,
                // so the scene view will be pure black

                cmd.Blit(source, tempTexture.Identifier());
                cmd.Blit(tempTexture.Identifier(), source, settings.material, 0);

                context.ExecuteCommandBuffer(cmd);
            }
            catch
            {
                Debug.LogError("Error");
            }
            cmd.Clear();
            CommandBufferPool.Release(cmd);
        }
    }

    Pass pass;
    RenderTargetHandle renderTextureHandle;
    public override void Create()
    {
        pass = new Pass("Underwater Effects");
        name = "Underwater Effects";
        pass.settings = settings;
        pass.renderPassEvent = settings.renderPassEvent;
    }
    public override void SetupRenderPasses(ScriptableRenderer renderer, in RenderingData renderingData)
    {
        var cameraColorTargetIdent = renderer.cameraColorTarget;
        pass.Setup(cameraColorTargetIdent);
    }

    public override void AddRenderPasses(ScriptableRenderer renderer, ref RenderingData renderingData)
    {
        renderer.EnqueuePass(pass);
    }
}

How may I fix these errors?