New high-scale data infrastructure projects I am aware of mostly seem to be C++ (often C++20). A bit of Rust, which I’ve used, and Zig but most of the hardcore stuff is still done in C++ and will be for the foreseeable future.

It is easy to forget that the state-of-the-art implementations of a lot of systems software is not open source. They don’t struggle to attract contributors because of language choices, being on the bleeding edge of computer science is selling point enough.

There's a "point of no return" when you start to struggle to hire anyone on your teams because no one knows the language and no one is willing to learn. But C++ is very far from it.