My understanding is that the device language should be set via: Settings > General > Language & Region. My device shows "English" as the language, however when I open my app, certain text such as the Apple sign-in method, and the "back" button for navigation links is in Arabic. I checked this by printing out the NSLocale.current.languageCode value, and ensured it was "ar", which did not match my expectation of "en".
I tried toggling the language from english to french, and back again to english, but the words never changed from arabic to anything else. I've also tried rebooting the simulator, erasing all content and settings, and using different target devices (iphone 13 and 11).