There was once a spokesman for the Chareidim in Eretz Yisrael who claimed that there are no Chareidim in the US because in the US, Jews eat bagels with cream cheese and lox which (according to this person) is clearly against halacha.
I think that the Bais Yosef says that you can’t eat fish with milk, but others (I think either the Shach or the Taz or both) claim it’s a taus sofrim or something. So Litvaks hold it’s okay, but many Sefardim and I think Chassidim hold it’s assur. The man who said that was Chassidish and I guess he hadn’t learned Hilchos Basar B’Chalav so he didn’t realize that there are other legitimate opinions.