In a previous question, you write that one cannot say brich hu during pesukei dezimra because of hefsek. Is it permissible to answer brich hu to the kaddish after hashkiveinu at maariv? Isn’t that a stronger hefsek than psukei dezimra?

Shalom, No, it's not a problem to answer brich-hu to your chazan's kaddish during ma'riv after hashkivenu, because that's exactly what the rabbi's instituted. On the other hand, if you hear the kaddish of another minyan at that time you wouldn't answer brich hu a second time. With Love of Israel, Rav Ari Shvat