Memory leak of accessChecker.isGranted ??

[Whisper40]

Version 9

I'm using this to display a button depending on user roles :

              <button *ngIf="(accessChecker.isGranted('edit', 'mep') | async)" class="multiple-action-button" nbButton status="info" type="button" (click)="editComponentOfMep(element)" title="Edition du composant de la MEP" size="small"><i class="fas fa-edit fa-lg"></i></button>

It is calling this method :

@Injectable()
export class NbSimpleRoleProvider extends NbRoleProvider {

  getRole(): Observable<string> {
    return this.authService.onTokenChange()
      .pipe(
        map((token: NbAuthJWTToken) => {
          console.log('Ton role est : ' + token.getPayload().roles[0].authority);     // Calling so much time this !
          return token.isValid() ? token.getPayload().roles[0].authority : 'GUEST';
        }),
      );
  }
..
..
..
}

The problem is that the page is calling so many times "accessChecker.isGranted" ! For each row of my table it calls the accessChecker, and if i keep the mouse on the button without doing anything else, it keep calling "accessChecker.isGranted" ! So thousand of calls in few seconds..