Capacitor 6升级后iOS端FCM推送报400无效注册令牌问题排查

我们有一个Ionic/Capacitor应用，此前Firebase FCM推送通知功能完全正常。近期升级到Capacitor 6，重建应用并重装了@capacitor/push-notifications插件，完成各类项目文件配置后，Android端运行正常，但iOS端发送推送通知时返回以下400错误：

HTTP/1.1 400 Bad Request
Vary: Origin
Vary: X-Origin
Vary: Referer
Content-Type: application/json; charset=UTF-8

{
"error": {
"code": 400,
"message": "The registration token is not a valid FCM registration token",
"status": "INVALID_ARGUMENT",
"details": [
  {
    "@type": "type.googleapis.com/google.firebase.fcm.v1.FcmError",
    "errorCode": "INVALID_ARGUMENT"
  }
]
}
}

服务器端发送通知的逻辑未做任何改动，因此问题显然出在iOS配置上。以下是我们在Xcode中完成的配置：

Podfile配置 #

target 'App' do
  capacitor_pods
  # add your pods here
  pod 'Firebase/Messaging'
end

AppDelegate配置 #

// Push notifications
import Firebase

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

func application(_ application: UIApplication, didFinishLaunchingWithOptions
    launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
    // Override point for customization after application launch

    // Push Notifications
    FirebaseApp.configure()

    return true
}

func application(_ application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: Data) {
  NotificationCenter.default.post(name: .capacitorDidRegisterForRemoteNotifications, object: deviceToken)
}

func application(_ application: UIApplication, didFailToRegisterForRemoteNotificationsWithError error: Error) {
   NotificationCenter.default.post(name: .capacitorDidFailToRegisterForRemoteNotifications, object: error)
}

本地运行日志 #

通过Xcode在本地设备运行应用时，注册并获取令牌的日志显示正常：

[log] FCM - register: granted
[log] FCM - registration: {"value":"7A868F9E49853DA0F175ABDCE683310CC279306B4B00B579DA94690273CE7A3A"}

我们确认服务器端使用的正是刚获取到的该令牌，但仍报错。请问遗漏了哪些配置？

内容的提问来源于stack exchange，提问作者Mike Darling