Rust? Go? Ruby on Rockets? Fortran++? No, no, no, and no.
We don't use trendy languages. The server core is written in C. It always has been, and always will be. From the original CP/M implementation in 1981 to today's unix-based powerhouse, it's all C, all the time.
The web front end uses JavaScript, of course, because that's what's in your browser.