nbwpuk, "Script loading strategies are now employed in core and bundled #themes to improve #performance of loading scripts with defer and async attributes. Additionally, scripts on the frontend and login screen are now constructed using script helper functions, making it possible to utilize Content Security Policy to harden against any XSS #vulnerabilities."
Script loading changes in WordPress 6.4 – Make #WordPress Core https://make.wordpress.org/core/2023/10/17/script-loading-changes-in-wordpress-6-4/