change your default extends FormRequest to your customize FormRequest (API ONLY)

FormRequest.php

<?php

namespace App\Http\Requests\Api;

use Illuminate\Http\Request;
use Illuminate\Http\JsonResponse;
use Illuminate\Contracts\Validation\Validator;
use Illuminate\Validation\ValidationException;
use Illuminate\Http\Exceptions\HttpResponseException;
use Illuminate\Foundation\Http\FormRequest as LaravelFormRequest;

abstract class FormRequest extends LaravelFormRequest
{
    /**
     * Get the validation rules that apply to the request.
     *
     * @return array
     */
    abstract public function rules(Request $request);

    /**
     * Determine if the user is authorized to make this request.
     *
     * @return bool
     */
    abstract public function authorize();

    /**
     * Handle a failed validation attempt.
     *
     * @param  \Illuminate\Contracts\Validation\Validator $validator
     * @return void
     *
     * @throws \Illuminate\Validation\ValidationException
     */
    protected function failedValidation(Validator $validator)
    {
        $errors = (new ValidationException($validator))->errors();

        $transformed = [];

        foreach ($errors as $field => $message) {
            $transformed[] = [
                'field' => $field,
                'message' => $message[0]
            ];
        }

        throw new HttpResponseException(
            response()->json([
                'success' => false,
                'status' => 'error_validasi',
                'message' => 'Terjadi error saat mengirimkan request',
                'errors' => $transformed,
                'data' => null,
            ], JsonResponse::HTTP_UNPROCESSABLE_ENTITY)
        );
    }
}