There are many separate processes which can push a question to the top. Several of them are credited to Community.
I guess you have the "get more attention to unanswered question" process in mind, which pushes old questions with no upvoted answers to the top. This process hasn't changed.
What happened in this case was an edit to one of the answers of the question. Like every edit, it also pushes questions to the top of the list ordered by activity. Normally, edits will be credited to the account which created them. But there are some edits which are credited to the special "Community" account, for example
- when an anonymous user makes a suggested edit and the edit is approved, the edit is credited to community
- when an answer gets a spam flag by a moderator, or a certain amount of spam flags by users (I think 6 or 7), the answer gets deleted. The deletion is credited to the Community user.
I am sure that there are more actions credited to Community, but I don't remember all of them. In the case you are talking about, it seems that it was an edit suggested by an anonymous user that pushed the question.