Off the top of my head, Apollo's recreations of the action sheet, search bar, and navigation controller have subtle bugs. The action sheet is missing vibrancy and does not respond correctly to touch in/out events, nor does it give any sort of indication of being scrollable (it also does the "oreo" thing if you switch between appearances). The search bar does not animate correctly when navigating between view controllers and while collapsing has incorrect rounding and shading. It also fails to take user input or respond to touches at all during animations. Your custom navigation controller does not animate titles correctly, and its swipe handling is frustratingly divergent from the system's: it accepts swipes starting almost a centimeter from the edge and is far too sensitive to accidental flicks. Plus, stylistically, it should be using large titles in certain places but does not.

These might seem like minor things, and they probably are for most people, but as an heavy iOS user I have a very good sense for how system components look and function, and it drives me up a wall when people reimplement them but break or fail to support some of their behaviors (specifically: if your custom component is supposed to look like a system control, it better act exactly like one!). As an iOS engineer I also know that these parts of UIKit are the somewhat problematic to deal with, but I appreciate apps that take the time to get it right and I would have hoped that an app that prides itself on looking at home on iOS would have put in the effort to care about this as I do. Hope this helps.