Does std::move leave stack fragmented or is the stack rearranged after moving an object to the caller?

I have read several answers and and many articles about move semantic so it is simply a static cast to rvalue reference, this question is about its influence on the stack, so is the stack left fragmanted after move? or is it rearranged somehow? as the stack moved objects are not subject to stack unwinding. The following snippet runs fine:

#include <memory>
#include <cassert>

struct A {
    int x = 0;
};

struct B {
    A a;
};

void SetB(B& b) {
    A a1{6}; //pushing into the stack.
    A a2{7}; //pushing into the stack.
    b.a = std::move(a2);
}

int main()
{
    B b;
    SetB(b);
    assert( b.a.x == 7);
}

a2 is defined in SetB stack frame but still available after SetB is finished and the contorl back to main. However; a1 is not despite it is closer to main stack frame?