Laravel validation "Present" does not work

Question

I have created a FormRequest for updating a BlogPost as UpdateBlogRequest.

I set thumbnail as a "present" for validation. but when this input is empty I get "The thumbnail field must be present."

Also I added input file with thumbnail name in HTML form.

UpdateBlogRequest:

<?php

namespace App\Http\Requests\Blog;

use Illuminate\Foundation\Http\FormRequest;
use Illuminate\Validation\Rule;

class UpdateBlogRequest extends FormRequest
{
    /**
     * Determine if the user is authorized to make this request.
     *
     * @return bool
     */
    public function authorize()
    {
        return true;
    }

    /**
     * Get the validation rules that apply to the request.
     *
     * @return array<string, mixed>
     */
    public function rules()
    {
        return [
            'name' => [
                'required',
                Rule::unique('blogs', 'name')->ignore($this->blog),
            ],
            'body' => ['required'],
            'excerpt' => ['present'],
            'thumbnail' => ['present'],
        ];
    }
}

I expected does not show error message for thumbnail when is empty