ConvertRedirects.php

<?php

namespace App\Http\Middleware;

use Closure;
use Symfony\Component\HttpFoundation\RedirectResponse;

class ConvertRedirects
{
    public function handle($request, Closure $next)
    {
        $response = $next($request);

        if ($response instanceof RedirectResponse) {
            $response->setStatusCode(303);
        }

        return $response;
    }
}