I just notice that the Cup that my level 16 team participated in last season was level 20, i.e. cup level is 4 levels above my league level. But I never meet a strong team like your opponent. In my impression, my teams just faced some teams 2 level above us. Probably something have been changed.
BTW, I don't know how to check the level of the Cup in this season. Can any advise me?