Unable to set Cache-Control header in Laravel

I'm having an issue with setting the Cache-Control header in my Laravel application. No matter what I try, the browser always shows the following header:

Cache-Control: max-age=0, must-revalidate, no-cache, no-store, private

I've created a custom middleware called \App\Http\Middleware\SetCacheHeaders that looks like this:

class SetCacheHeaders
{
    /**
     * Handle an incoming request.
     */
    public function handle(Request $request, Closure $next): Response
    {
        $response = $next($request);

        if ($response instanceof \Illuminate\Http\Response) {
            $response->header('Cache-Control', 'public, max-age=7200');
            $response->setEtag(md5($response->getContent()));
        }

        return $response;
    }
}

I've also tried using the predefined Laravel middleware:

->middleware('cache.headers:public;max_age=7200;etag');

However, in both cases, only the Etag header is being set, and the Cache-Control header is not being modified.

I've read that this issue can be caused by PHP settings, so I've also updated my php.ini file to set session.cache_limiter = ''.

This application is hosted using Laravel Forge, so I'm wondering if that could be causing any issues with the cache settings.

I also tried setting the Cache-Control header directly in the Nginx configuration, which worked, but in this case, I ended up with two Cache-Control headers, which is not ideal.

Could you please help me understand why I'm unable to control the Cache-Control header in my Laravel application? I need to set the Back/forward cache functionality, and this is preventing me from doing so.

Any guidance would be greatly appreciated.