Problem validating img_perfil from the users table (the image is validated even without selecting any)

I am customizing the templates and controllers that Laravel automatically creates for you with the command:

php artisan make:auth

And well, I have it almost finished in a first version of what I want. But I have come across the following problem:
I have added several fields to the table usersthat Laravel creates by default, to customize it, including the img_perfil. The issue of migrations and the addition of new fields to the users table have not caused me any type of problem.
But the issue of the field img_perfildoes hinder me:

When validating it in the frontend part, it is set with a inputtype file:

                <div class="form-group row">
                    <label for="img_perfil" class="col-md-4 col-form-label text-md-right">Imagen de perfil</label>

                    <div class="col-md-6">
                        <input id="img_perfil" type="file" class="form-control @error('img_perfil') is-invalid @enderror" name="img_perfil" value="{{ old('img_perfil') }}" autocomplete="img_perfil">
                        @error('img_perfil')
                            <span class="invalid-feedback" role="alert">
                                <strong>{{ $message }}</strong>
                            </span>
                        @enderror
                    </div>
                </div>

In my backend validation ( fileControllers\Auth\RegisterController.php ) I have it as follows:

<?php

namespace App\Http\Controllers\Auth;

use App\User;
use App\Http\Controllers\Controller;
use Illuminate\Support\Facades\Hash;
use Illuminate\Support\Facades\Validator;
use Illuminate\Foundation\Auth\RegistersUsers;

class RegisterController extends Controller
{
    /*
    |--------------------------------------------------------------------------
    | Register Controller
    |--------------------------------------------------------------------------
    |
    | This controller handles the registration of new users as well as their
    | validation and creation. By default this controller uses a trait to
    | provide this functionality without requiring any additional code.
    |
    */

    use RegistersUsers;

    /**
     * Where to redirect users after registration.
     *
     * @var string
     */
    protected $redirectTo = '/home';

    /**
     * Create a new controller instance.
     *
     * @return void
     */
    public function __construct()
    {
        $this->middleware('guest');
    }

    /**
     * Get a validator for an incoming registration request.
     *
     * @param  array  $data
     * @return \Illuminate\Contracts\Validation\Validator
     */
    protected function validator(array $data)
    {
        return Validator::make($data, [
            'name' => ['required', 'string', 'max:255'],
            'email' => ['required', 'string', 'email', 'max:255', 'unique:users'],
            'password' => ['required', 'string', 'min:8', 'confirmed'],

            'apel_1'=>['string','max:255'],
            'apel_2'=>['string','max:255'],
            'user_name'=>['string','required','max:20','unique:users'],
            'img_perfil'=>['max:100000','mimes:jpg,png,jpeg,gif'],


        ]);
    }

    /**
     * Create a new user instance after a valid registration.
     *
     * @param  array  $data
     * @return \App\User
     */
    protected function create(array $data)
    {
        return User::create([
            'name' => $data['name'],
            'email' => $data['email'],
            'password' => Hash::make($data['password']),

            'apel_1' => $data['apel_1'],
            'apel_2' => $data['apel_2'],
            'user_name' => $data['user_name'],
            'img_perfil' => $data['img_perfil']

        ]);
    }
}

As can be seen, in the validation of the field img_perfilit is set as follows:

'img_perfil'=>['max:100000','mimes:jpg,png,jpeg,gif'],

It is understood that the validation that I do is: image size | extensions allowed I am not indicating that it is required, because when I do a test to insert user without selecting any photo it tells me:

The img profile must be a file of type: jpg, png, jpeg, gif.

But that should tell me if I have selected a photo. If there isn't, then it doesn't validate anything.