Etag Implementation in Magento2

this code I am using to set etag in header, I am able to set etag in response header but If-None-Match always coming empty. 1. Nginx Server 2. Magento Version – 2.4.8-P1

 $etag = md5($category->getId();

 $etagHeader = 'W/"' . $etag . '"';

 $this->response->setHeader('Etag', $etagHeader, true);
 $this->response->setHeader('Cache-Control', 'public, max-age=3600', true);
 $this->response->setHeader('Pragma', 'cache', true);

 if (trim($this->request->getHeader('If-None-Match')) === $etag) {
       $logger->info('ETag matches, returning 304');
       $this->response->setHttpResponseCode(304);
       $this->response->clearBody();
 }