Even with a straight 1 1/8″ steerer, there’s a (slight) flare at the base of the steerer
You’re right of course and it should be a 44/30 but, for my part, I’ve never seen an ec44/28.6 cup that isn’t actually a /30 marked for ease. Happy to be contradicted but I don’t think there is any such thing as an external top cup for 44mm (unless you’ve a 1.5 steerer or possibly overdrive?)
Geometry should be closer to standard if I could too.
A top cup wouldn’t do that.
Edit: beaten to it, and answered. Yes a slack set would be the right answer and explain the geometry change from a top cup. Though given the op’s question I doubt a slack set is the right answer simply because the chances of having a slack set knowing what it is and how it works but not knowing it replaced a zs44 are I suspect, slim.