Bluesky doesn't even have a following feed like twitter (where only posts by people you follow show up)
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).
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:
https://bsky.app/settings/following-feed
Also if you just want to not see them sometimes, there's a feed you can add called 'OnlyPosts':
And that only-posts feed is even stranger. It only shows 3 days. People I follow have months of posts.
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.