That’s how “active” works afaik. “Active” looks at latest comment, so if it’s an old post, it will still go to the top because there are recent comments.
I think Active made sense for Lemmy initially, since it works a lot more like a phpBB forum board where each new comment bumps the thread to the top. I guess that made sense when Lemmy servers were relatively quiet.
Now that many new users are coming from Reddit and expecting it to behave accordingly, it makes more sense to switch to Hot as the default.
That I agree with. But as others have said in the thread, I think it made sense when Lemmy wasn't as big as it's becoming now. It might even become a setting that admins can set, just like now an admin can set which to show by default; local or all for listing posts.