I guess this happened at least 9 months ago, but I just noticed. https://www.linkedin.com/help/linkedin/forum/question/509609/viewing-shared-connections-of-a-3rd-level-connection?lang=en
I suspect that this took away business from LinkedIn's customers (recruiters) since a candidate could reach out to someone at the company instead of going through a recruiter.
LinkedIn was bad before but now it is totally useless to me.