This is not true. Even the Free plan has DDoS protection. L3/L4 (TCP SYN floods, UDP reflection attacks and similar) filtering is built-in and always-on, by default. CloudFront terminates TLS, and only forwards valid HTTP(S) requests to cache / origin.

The "Always-on DDoS Protection" on L7 is protection against massive requests spikes, built natively into CloudFront. Detection and mitigation of these attacks happens inline.

The "Advanced DDoS Protection" on L7 is adjustable, score-based DDoS protection configurable on AWS WAF (https://aws.amazon.com/blogs/networking-and-content-delivery...). Detection and mitigation of these attacks happens within seconds.

the pricing page says it comes with "Always-on DDoS Protection" but not "Advanced DDoS Protection"

I have no idea what these terms mean in practice