When a user is updated/deleted the cache of the directory is cleared but the cache of the same directory in the site app is not cleared.
This leads to false information in cache that can result in user being unable to access the app in the following scenario :
- log in the FO app with email
- delete the user from the BO app
- create a new user in the BO app with the same mail but different login
- try to log in the FO app with email -> AccessDenied