I think it has to do with swift runtime deprecations. I have an objective-c app that is as old as the AppStore and I haven't updated it for 8 years [1], Apple

I think it has to do with swift runtime deprecations. I have an objective-c app that is as old as the AppStore and I haven't updated it for 8 years [1], Apple even updated it once themselves somehow to support iOS 11. Another of my apps was removed with a similar vague explanation as the OP got and it was written using Swift [2]. While I understand that they might want to drop support for old runtimes the 30-day deadline is ridiculous. And if you miss it you need to re-submit the app and lose your ratings etc. I made nowhere near enough in the ~2 year period my app was available to justify spending the effort to modernize the project so I just let them remove it... [1]: https://apps.apple.com/us/app/seismometer/id288966259 https://apps.apple.com/us/app/seismometer/id288966259 [2]: https://github.com/jnordberg/triggy https://github.com/jnordberg/triggy