AWS WAF now enables you to select a specific version of a managed rule group within your web ACL, giving you the ability to test new rule updates safely and roll back to previously tested versions. When using a versioned managed rule group, you control when new rule updates are applied to your traffic. By default, you will continue to automatically receive rule updates to your managed rule group. You can change this behavior by manually selecting a version, enabling you to pause automatic updates or go back to a previous version. Once you select a specific version, you will no longer receive automatic updates but will remain on the selected version until it reaches end of life.
Source:: Amazon AWS