C++11 ambiguity between uniform initalization and initializer list

I found cases when a {}-list is interpreted in different ways that can lead to subtle bugs. For example in this program (g++ 10.2.1):

#include <vector>
#include <iostream>

struct A {
        int n1;
        int n2;
        //A(int _n1 = 0, int _n2 = 0): n1(_n1), n2(_n2) {}
};

int main() {
        std::vector<A> v;
        v.push_back({1,2});
        std::cout << v.size() << std::endl;
        v.insert(v.end(), {3,4});
        std::cout << v.size() << std::endl;
}

Without a constructor in A, insert adds one element. Defining the constructor, insert adds two elements, building an A object for every number. This is because insert (unlike push_back) has different overloads for a single object or an initializer list. Of course this is not the case if you explicitly write A{3,4}.

My questions:

• Is there a coherent line of reasoning to be aware of such cases?
• Are there other similar cases you know?