I realized that I am using an Apache server with Magento, where there is typically one .htaccess file for different directories. I am receiving CSS and JS files from the pub/static/ directory, which also contains its own .htaccess file. After changing the configuration in that file, the request headers in my browser are updated. Please ensure that you update the .htaccess file for the correct directory. If you modify the .htaccess file in other directories, such as the Magento installation directory, instead of the directory from which the browser is receiving the data, it won't affect the browser headers (in my scenario). This can save time for others.