Ask HN: Exciting things to study(in CS) to break out of plateau?

Hey, everybody! I want to ask you for some advice.

I have been learning to code for a few years now, I've learned some programming languages, I've built some cool projects. I know things about Computer Science, but I am far from being a master of my craft.

Now I feel like I hit a plateau. I've got a bunch of things to do and to study, but it's going kinda slow, and feels kinda stale.

So I am looking for new and exciting avenues to exlore, I want to get "in the zone" of rapidly learning new skills and exploring unfamiliar subjects.

Can you suggest some new, cool, interesting things to do and explore? It can be a project or a book or a challenge, or some niche of CS I haven't thought of yet.

What gets you excited? What do you crave to learn?