ldc-crm/database/seeders/UserSeeder.php

<?php

namespace Database\Seeders;

use App\Models\Brand;
use App\Models\User;
use Illuminate\Database\Seeder;

class UserSeeder extends Seeder
{
    /**
     * Run the database seeds.
     *
     * @return void
     */
    public function run(): void
    {
        User::factory(20)->create()->each(function ($user) {
            $brands = Brand::inRandomOrder()->take(rand(1, 3))->get()->modelKeys();
            $user->brands()->attach($brands);
        });
    }
}