Meta does both. It has long been said that businesses have little organic reach in Meta’s platforms, as an incentive for them to use ads.

I’m not a big poster at all, but ran into this precise issue.

They analyze the video posts on instagram. If they detect the video has even a small amount of commercial value, they classify it as branded content and you need to pay for it to get promoted.

For all the creepy People You May Know stuff they don't even bother connecting people properly even on people's personal pages https://news.ycombinator.com/item?id=14147719