The release notes for 7.0.0 states that:

onNotificationOpenedApp and getInitialNotification from RNFB Messaging will no longer trigger as Notifee will handle the event. Should not require any code changes to these RNFB event handlers, as events on Android will continue to work as normal

This is not mentioned anywhere else and I just spent 2 days debugging this until arriving at this issue. It seems that the getInitialNotification part is mentioned in the Notifee docs but I couldn't find any mentions of onNotificationOpenedApp being deprecated for iOS. Would it be possible to mention this somewhere in the docs of either RN Firebase or Notifee?