We use a webhook to receive comments that mention users who have authenticated via our app, this has worked for years. Now, since 8/28 the username field of the commenter mentioning the authenticated user is no longer being returned in the comment data.

We are using Facebook Login for Business with the instagram_manage_comments permission, which according to this documentation is correct:

https://developers.facebook.com/docs/instagram-platform/instagram-graph-api/reference/ig-comment

We are seeing in the developer community site other people are having this issue.