Giving "Add user" privilege to members also gives it to anonymous users

How to reproduce:

1. In "Administration -> Configuration -> Organic groups -> OG permissions overview -> Node - Group permissions", add the "Add user" privilege to group members.
2. As an anonymous user, open a group URL in the Drupal frontend. This page now has an added tab "Administer group" with an option to add members to the group.

In my understanding, this is non-desired behavior because I did not give the "Add user" privilege to non-members of the group. (And even if I had done so, it should probably still be forbidden for anonymous users?)