URLSession didReceiveChallenge failing on iOS 17

We're seeing server trust failures with iOS 17 that we don't see with iOS 16, particularly in debugging, when we build with Xcode 15. We handle

func urlSession(_ session: URLSession,
                didReceive challenge: URLAuthenticationChallenge,
                completionHandler: @escaping (URLSession.AuthChallengeDisposition, URLCredential?) -> Void)

and choose to deal with recoverable server trust failures of particular kinds ourselves. After our checks we end up calling the completion handler:

  let credential = URLCredential(trust: serverTrust)
  completionHandler(.useCredential, credential)

And everything continues.

This is working on macOS Venture and earlier and iOS 16 and earlier. It also works if we install our current release build on iOS 17. If we build with Xcode 15 and test on iOS 17 then calling the completion handler with .useCredential ends up failing with a -1200 error, and a message about a recoverable trust failure.

Has anyone else seen this behavior? Does anyone know if this is related to just Xcode 15, or to Xcode 15 + an interaction with iOS 17? Maybe the SDKs used with Xcode 15 are being stricter? In any case it would seem that saying .useCredential should cause it to .use the credential...