Consider this code:

#include <stdio.h>
#include <float.h>

int main() {
    double a = 100.0;
    printf("a: %.6lf\n", a);
    return 0;
}

It should print 100.000000 right? It does on https://www.onlinegdb.com/online_c_compiler, it does on my local computer. But on codeforces: https://i.imgur.com/P2CCY7Q.png

I'm more of a Python user so maybe I'm missing something big and it's actually not a bug?