The add-in will not be removed from "Allowed". Your "Allowed" shows that the last time this add-in requested and received a legacy token was 2/6 (February 6) so that is basically an "old entry" for your case. This add-in therefore is not actively using legacy tokens since February, even though it is still asking for legacy tokens (last time on 5/27). But if the add-in works, what likely is going on is that the add-in has a failback mechanism to request the legacy token, which then fails and then it uses NAA to auth so it keeps working even though it was "blocked" for legacy token issuance.
If your add-in works, you should not have to do anything.