Symfony 4 HTTP Cache Headers not same in profiler and browser

For a website development, I try to use Symfony 4 HTTP cache described in documentation.

I created an CacheKernel called in index.php like this :

namespace App;

use Symfony\Bundle\FrameworkBundle\HttpCache\HttpCache;

class CacheKernel extends HttpCache
{

}

// index.php
$kernel = new Kernel($_SERVER['APP_ENV'], (bool) $_SERVER['APP_DEBUG']);
$kernel = new CacheKernel($kernel);
$request = Request::createFromGlobals();

In homepage action:

$response->setPublic();
$response->setMaxAge(3600);
$response->headers->addCacheControlDirective('must-revalidate', true);

return $response;

In profiler, headers are sets :

cache-control "max-age=3600, must-revalidate, public"

But in browser, headers are not same, and I think cache is not stored :

Cache-Control: max-age=0, must-revalidate, private

Have you got some ides to understand why headers are not same and why cache is not working please ?

And how can I make be sure cache is working, is there some logs ?

Thanks a lot for helping

source https://stackoverflow.com/questions/68963729/symfony-4-http-cache-headers-not-same-in-profiler-and-browser