The two feeds on Bluesky are "Following" (only posts by people you follow show up) and "Discover" (largely dominated by posts by people you don't follow). There are two huge tabs at the top of your feed to switch between them.
If you are following 0 people, the "Following" feed acts similar to the "Discover" feed. As soon as you follow a single person, it works as you'd expect (only showing content from people you've followed).
Something is terribly wrong, then; my following feed shows posts (and certain replies) from people I follow in reverse chronological order, and nothing else, ever.
Are you maybe seeing things that have been reposted by people you follow? There's a lot of that, but those still count as "posts from people you follow". If you want to exclude those, there are settings at the following link:
You can turn off retweets and replies. If you're going to use software with only the default options, at least don't spread misinformation about what you failed to try to learn.
I am not talking about replies and retweets. Those are literally posts from people I dont follow and are not reposts. 4 day old post is followed by posts posted only hours ago.
Maybe you're looking at the "Discover" tab and not the default one which is called "Following".
One scenario where chronology is confusing is when a reply to an earlier tweet takes its chronological place in the timeline but also includes the earlier tweet for context.
I am looking at the tab called Following. I even turned off quotes, replies and mentions. It still shows only 3 days (yesterday it was 4 days) of posts by followers followed by random crap.
If you are following 0 people, the "Following" feed acts similar to the "Discover" feed. As soon as you follow a single person, it works as you'd expect (only showing content from people you've followed).