Need help to understand lifetime management

[FlyinCow]

godbolt case

#include <print>
#include <vector>

#include "proxy/proxy.h"

PRO_DEF_MEM_DISPATCH(MemEval, eval);
struct Curve : pro::facade_builder                                //
               ::add_convention<MemEval, double(double)>          //
               ::support_copy<pro::constraint_level::nontrivial>  //
               ::build {};

using CurveP = pro::proxy<Curve>;

class SomeCurve {
   public:
    double eval(double t) { return t; }
    ~SomeCurve() { std::println("destruct C"); }
};

PRO_DEF_MEM_DISPATCH(MemDrawOn, draw_on);
struct Drawable : pro::facade_builder                                //
                  ::add_convention<MemDrawOn, void()>                //
                  ::support_copy<pro::constraint_level::nontrivial>  //
                  ::build {};

using DrawableP = pro::proxy<Drawable>;

class Drawer {
   public:
    void draw_on() {}
    Drawer(CurveP c) : c(c) {};
    ~Drawer() { std::println("destruct D"); }

   private:
    CurveP c;
};

class Canvas {
   public:
    void add_drawable(DrawableP d) { drawers.push_back(d); }

   private:
    std::vector<DrawableP> drawers;
};

int main() {
    Canvas cv;
    SomeCurve c;
    cv.add_drawable(pro::make_proxy<Drawable, Drawer>(&c));
}

There are one call of desctruction of SomeCurve which is the SomeCurve c; in int main(), but two calls of destruction of Drawer, and I wonder why, which ones are the Drawer that is destructed.