Why are some posts in a facebook group not showing up in the feed?

Question

Facebook

Hello. I am importing news from the group https://www.facebook.com/globemedias to the site. When requesting group posts via the API (feed or posts method), more posts are returned than in the group feed. Later I found these posts in the group itself, but for some reason they are not all displayed.
Example:
https://www.facebook.com/globemedias/posts/1584774...
https://www.facebook.com/globemedias/posts/1584774...
https://www.facebook.com/globemedias/ posts/1584773...
https://www.facebook.com/globemedias/posts/1584773...
https://www.facebook.com/globemedias/posts/1584737...
And only these are displayed in the feed:
https ://www.facebook.com/globemedias/posts/1584774...
https://www.facebook.com/globemedias/posts/1584773...

All posts come in responses from the server. I checked the parameters is_visible (all false) and is_published (all true) for post objects, but they are all the same. Posts are not hidden from the timeline because if they were hidden, then they would not be transmitted through the API (Verified).
Why are these posts hidden from the group feed?

Answer 1

FB has a very interesting algorithm for including posts in the feed. Not all messages reach users' feeds, this is normal for FB.