I'm seeing this issue too. I'm surprised that the default behavior is this and that it requires configuration now? I also had to set it for all appearance types to make it look better, but there are still cases where the appearance is strange especially in the transitions between view controllers.

We faced a similar problem and are considering resolving it with making sure that we always set the background of the view of our view controllers to something other than clear such as systembackgroundcolor, and ensuring that all of our view controllers use UIRectEdgeAll. Previously some view controllers and especially WKWebViews had a clear background and UIRectEdgeNone. I'd be curious to hear if this helps for anyone else. I like this approach more as it feels less invasive than changing the appearance of the navigation bar.