It’s easy for really old posts to get necro’d in Active sort. Not necessarily a bad thing, but if you use the “feed” to keep up with the latest then it’ll cloud your listings a bit. A lot of people don’t look at the post date right away (especially those of us from alien site since we’re still operating on old habits).
Hot also had a bug that pushed old posts up, IIRC? Maybe i’m thinking of Active; I can’t remember off the top of my head as I type this. Anyway I think Active is based on recent comment activity and Hot is based on recent voting activity. Nothing wrong with either, but I am honestly appreciating the “Top X hours” methods to keep up with recent news and events and to keep things fresh.
We’re still in the “oh shit activity has increased by a factor of a thousand, we need to make the database not crash” phase of development of Lemmy (and kbin) so I’d expect that eventually the feed sorts will be looked at and tweaked. Just needs a bit of attention to get what you are looking for at the moment.