I have a very specific issue that happens only on iOS Simulator version 18.4. It does NOT happen when I run my app on a real iOS 18.4 device through Testflight. My app displays a WebView (courtesy of Capacitor, url scheme capacitor://). Inside that Webview I'm using Firebase JS API (11.2.0) and calling signInWithEmailAndPassword, which works well in all other contexts, i.e. browser, Android webview, iOS webview in all other Simulator versions, and on real devices. Only when running in Simulator 18.4, I get a failed network request: cannot parse response Fetch API cannot load https://identitytoolkit.googleapis.com/v1/accounts:signInWithPassword?... due to access control checks. Failed to load resource: cannot parse reponse error: FirebaseError: (auth/network-request-failed) Everything is working correctly for both: Capacitor app webview installed on a real 18.4 device with Testflight Safari (non-webview) in the 18.4 Simulator The issue is severe for us, because we are unable to develop our app and test it in the simulator on 18.4 Simulator before pushing it through Testflight internal release. Request headers on the failed request (no response status or headers available). Request Accept: / Content-Type: application/json Origin: capacitor://localhost Sec-Fetch-Dest: empty Sec-Fetch-Mode: cors Sec-Fetch-Site: cross-site User-Agent: Mozilla/5.0 (iPhone; CPU iPhone OS 18_4 like Mac OS X) - AppleWebKit/605.1.15 (KHTML, like Gecko) Mobile/15E148 X-Client-Version: Mobile/JsCore/11.2.0/FirebaseCore-web X-Firebase-Client: (...)