C++ variable initializes even though the copy constructor is deleted

The code below works unexpectedly!

class CameraBuffer;
class CameraBufferAccessor{
  friend CameraBuffer;
  private:
    CameraBufferAccessor(const int &data, const int &mutex);
  public:
    CameraBufferAccessor() = default;
    CameraBufferAccessor(const CameraBufferAccessor &) = delete;
    CameraBufferAccessor(CameraBufferAccessor &&) = delete;
    void operator=(const CameraBufferAccessor &other) = delete;
    void operator=(CameraBufferAccessor &&other) = delete;
};
class CameraBuffer {
  public:
    const CameraBufferAccessor getReadAccess() const {
        return {1, 2};
    }
};
int main() {
    auto buffer = CameraBuffer();
    CameraBufferAccessor a = buffer.getReadAccess();
    CameraBufferAccessor b = a;

here CameraBufferAccessor b = a; as expected throws error since copy constructor is explicitly deleted.

but something happens that i donot expect and i have searching for it so far no explaianation. the line CameraBufferAccessor a = buffer.getReadAccess(); just works although it uses a function which has non-reference return, which itself is supposed to make use of Copy Constructor, secondly the returned CameraBufferAccessor should be copied into a initializing a using Copy/Move constructor once again, but it compiles and doesn't throw.

I heard That the compiler for optimization purposes is allowed to bypass copy construction when necessary, if that's the case here, how am I supposed to tell when compiler does that?

I thought that it was due to the curly braces in return statement of getReadAccess which directly initialized the return value, So I tried return CameraBufferAccessor(1, 2); but it still works. maybe compiler optimization?