Any open source infrastructure projects under active development?

One thing that I really appreciate about the blockchain and AI communities is that there is a lot of open source activity in these spaces. It seems feasible to find an interesting project on GitHub, get a deep understanding of it, and take up an issue to start contributing to it.

I wonder if there are any good examples of open source projects in infrastructure that have a similar amount of activity? When I am talking about "infrastructure" here, I'm thinking of things like: pub-sub, event streaming, distributed coordination, and/or data distribution systems.

I've started to get the feeling that open source infrastructure is relatively static now given all of the work that went into it during the last two decades, so there isn't much going on outside of the largest companies that need to scale existing solutions.