The C23 edition of Modern C

Most important aspect of C is its portability. From small microcontrollers to almost any computing platform. I doubt that any new version of C will see that much adoption.

If I want to live on cutting edge I would rather use C++2x or Rust rather than C.

Am I missing something? What benefit this supposedly modern C offers?

One advantage of writing C code is that you don't have annoying discussions about what idiomatic code is supposed to look like, and what language subset is the right one ;)

For the cutting edge I would recommend Zig btw, much less language complexity than both modern C++ and Rust.

One good but less visible side effect of C23 is that it harmonizes more syntax with C++ (like ... = {} vs {0}) which makes it a bit less annoying for us C library maintainers to support the people how want to compile their C code with a C++ compiler.

There is enough material in C, and related compiler extensions, to have similar discussions, starting from where to place brackets.