To take advantage of new security features and bug fixes, you need to stay up-to-date with the latest software. Before you do anything else, update your cluster with latest version of Scylla. Also take the time to ensure that your operating system and libraries are up-to-date as well.
Security-conscientious developers and infrastructure maintainers can protect against side-channel attacks by minimizing the amount of shared infrastructure. This means VMs and Container infrastructure. This was always a theoretical concern, but the new flaws catapult this front and center to the main stage.