GraphQL (advanced). Already been using it for 4 years now (yes back when there was no tooling nor best practices) but I decided to go further in the schema design thinking and bought Production-Ready GraphQL to help with it. Strongly recommend the book as it goes quite deep on the subject.

Also experimenting with my 4th home-brewed beer.

"Soft skill"-wise I spend time helping people with good (so I hope) advice and recommendations and a bit of interview mentoring to enter the software development industry. Makes you learn a lot about yourself and how you can motivate and help people big time with only a tiny amount of your time and energy, just sharing stuff you know.