This looks similar to a previous issue:
https://forum.inaturalist.org/t/ios-app-will-not-open-on-iphone-7/43318/
However, those were with a different iOS version (12.5.7), so I’ve let as a separate bug report for now.
That issue hasn’t been resolved to the best of my knowledge due to lack of info and that no one could become a beta tester due to iOS being pre v13. But since iOS is >= 13 here, maybe beta testing will help, see