TestFlight now requires iOS 13. iOS 12 and below considered obsolescent

Do the older versions of the TestFlight app still work? The App Store allows you to download the latest version of any app that's compatible with your device; I assume the TestFlight app is no different in this regard.

That is, while the TestFlight app now requires iOS 13, I assume that iOS 12 users are still able to access betas of apps that themselves still run on iOS 12, via an older version of the TestFlight app.