Read the blog post: https://silvanhagen.com/writing/custom-driver-favicon-fetcher/

Creator.php

<?php

namespace App\Models;

use AshAllenDesign\FaviconFetcher\Facades\Favicon;
use Illuminate\Database\Eloquent\Factories\HasFactory;
use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\Relations\HasMany;
use Illuminate\Support\Facades\Storage;

class Creator extends Model
{
    protected static function booted()
    {
        static::saving(function ($creator) {
            $creator->fetchFavicon($creator->link);
        });
    }

    public function fetchFavicon(?string $url): void
    {
        // If the link has not been changed and is not null, return early
        if (! $this->isDirty('link') && $url !== null) {
            return;
        }

        // If the avatar_url is set, delete the existing image
        if ($this->avatar_url) {
            Storage::disk('public')->delete($this->avatar_url);
            $this->avatar_url = null;
        }

        // If the link is null, we're done
        if ($url === null) {
            return;
        }

        $favicon_path = Favicon::driver('unavatar-services')
            ->fetchOr($url, 'https://wireinthewild.com/favicon.png')
            ->store('avatars', 'public');

        if ($favicon_path) {
            $this->avatar_url = $favicon_path;
        }
    }
}