On your 'App Store Connect' page, you notice one of your apps has been 'Removed from Sale', and you would like to know why this has happened and what are the steps to resolve it.
Apple requires you to republish your app at least every 2 years to stay up to date with their latest iOS SDK, so a likely reason for this issue is the app not being republished for a long time. Our recommendation is to republish your apps every 3 to 6 months, as stated in our When do I need to Republish an App? article.
If you wish to know the exact reason why the app was removed from sale, you will need to get in touch directly with Apple Developer Support as they are the only ones who possess this information.
To reestablish your app on Apple Store, you will have to republish it by following the steps presented in the Publish Apple App on Apple's App Store article.