Apple prevented transfer of the applications between developers if the application used iCloud containers or key-value storage. Well, not anymore.
Now Apple allows this kind of application transfer. This provides an opportunities to indie developers to sell their apps to other developers even if they were using iCloud.
Apple Developer: App Store Connect Update
App Store Connect Help: App transfer overview
Developer:Consider using iCloud if ability to transfer the app was stopping from it previously.
QA engineer:Business as usual.
PM/DM:Consider using iCloud features within the application.