I think quite a lot has happened to Cycles since then.
Honestly, not that much has happened with Cycles since 2.7x. It may be hard to believe but for a period of about 5 years Cycles was under heavy development as it built up the majority of modern render engine features. But that period ended several years ago and it’s primarily been small updates and optimizations since late 2.7x versions.
Eevee is getting most of the render-centric development in recent years.
I say that because you can still learn the vast majority of Cycles features from 2.7x material.
