When the prevent using old password option is set, user will not be able to see the notification message in https://github.com/ezsystems/ezplatform-user/blob/master/src/bundle/Controller/PasswordResetController.php#L212  as the user will be redirected to the password reset form again. The user would not understand what's happened exactly A new generic ErrorView($e->getMessage()) taken into account the error message would probably solve this issue.

After using another password and successful login, all notifications(flash messages) will be displayed in the dashboard. It depends on the number of failed attempts (same=old password during reset attempts).