Let's say it another way.

When people, tech news, non-tech people, say "The FACEBOOK algorithm" or the "TIKTOK" algorithm, they are talking about the opaque recommendation engine that works on each individual user based on the likes, preferences, viewed pages, and probably things like location, time spent looking at a random video, and a hundred other things.

It's about individual recommendations based on lots of datapoints vs. a more direct sorting based on global trending.