Something weird about Rek’Sai’s ultimate.

Something I’ve noticed from playing rek’sai is that after you ult someone you’re unable to attack for awhile. This just bugs me because if you’re ultimate doesn’t finish them off you’re left vulnerable long enough for you to get cc’d down and lose a kill that you could’ve gotten otherwise. Similar abilities such as nocturne ult and lee sin q don’t have this. If it’s for balancing purposes, most of the time you’re ult will be flashed anyway while the two skills mentioned above can not which I think is balanced enough. A minor issue sure but I hope it eventually does get fixed.