iOS 13 - Buggy Large Title UINavigationBar while pushing

I had the same issue. Try to set navigationItem.largeTitleDisplayMode to .always for your first VC and then .never for your second VC with prefersLargeTitles = true in both cases.

The reason is written from Apple Doc:

If the prefersLargeTitles property of the navigation bar is false, this property has no effect and the navigation item’s title is always displayed as a small title.

Which is causing the animation glitch, and it's not a iOS13 bug only, on iOS12/11 it's already the case it's just the other way around (the animation glitch is happening when dismissing from the secondVC back to the firstVC).

I wrote an article that explain a bit more about this: