There are five different reasons why NetNewsWire switched back to UIKit from SwiftUI. In this post, Brent talks about why SwiftUI isn't ready for them quite yet. If you are considering switching anything to SwiftUI, this is a must-read.
I believe SwiftUI is the future, but these points make it clear it has a little ways to go to work for a majority of apps. That's understandable and the main reason I wait a bit before I just into something new.
SwiftUI Is Still the Future by Brent Simmons