va_start with GCC 13.2, flags not enabling C23 for this method

Question

I am trying to use this functionality, specifically the C23 version so I don't need to pass the second parameter.

   void va_start( va_list ap, ... ); //(since C23)

When running the provider example on cppreference, and choosing GCC 13.1(C23), it works as expected. I installed GCC 13.2 in my machine and I haven't been able to reproduce this.

I also checked the include files that were installed, and the intended implementation is there.

I have tried the compile flags suggested by gnu, -std=c++23, -std=c++2b, -std=c++23, -std=gnu++23 (even the -enable-experimental) and none of them seems to work. I wonder what is it that I am missing.

va_start

    #include <stdio.h>
    #include <stdarg.h>
     
    int add_nums_C99(int count, ...)
    {
        int result = 0;
        va_list args;
        va_start(args, count); // count can be omitted since C23
     
        for (int i = 0; i < count; ++i) {
            result += va_arg(args, int);
        }
     
        va_end(args);
        return result;
    }
     
    #if __STDC_VERSION__ > 201710L
    // Same as above, valid since C23
    int add_nums_C23(...)
    {
        int result = 0;
        va_list args;
        va_start(args);
     
        int count = va_arg(args, int);
        for (int i = 0; i < count; ++i) {
            result += va_arg(args, int);
        }
     
        va_end(args);
        return result;
    }
    #endif
     
    int main(void)
    {
        printf("%d\n", add_nums_C99(4, 25, 25, 50, 50));
    #if __STDC_VERSION__ > 201710L
        printf("%d\n", add_nums_C23(4, 25, 25, 50, 50));
    #endif
    }

Running the same snippet from cppreference on godbolt and adding those flags don't seem to work either.