When compiling with gcc, overloaded new operator is not called for std::string

This program (compiled with option -std=c++17)

#include <stdio.h>
#include <string>
void* operator new(std::size_t nrOfBytes) {
    printf("allocate %zd bytes on heap\n", nrOfBytes);
    void* p = malloc(nrOfBytes);
    if (p) {
        return p;
    } else {
       throw std::bad_alloc{};
    }
}
int main() {
    // new operator is called when compiled with Clang or MSVS or GCC 
    int* i = new int;
    delete i;
    // new operator is not called when compiled with GCC
    // but is called with Clang and MSVS 
    std::string str(2000, 'x');
    return 0;
}

when compiled with Clang or MSVS, prints:

allocate 4 bytes on heap

allocate 2016 bytes on heap

However, when compiled with GCC (Version 9.2.0 provided by MSYS on Windows) it only prints:

allocate 4 bytes on heap

I am aware of short string optimization in GCC/libc++, but aren't 2000 chars too many for a short string? Is it a matter of SSO at all?