How does the system determine a "Highly active question." -- I think 6 year old questions are not Highly active

Question

I've encountered multiple questions that are marked as being highly active and requiring a higher reputation to answer. The only problem is that some(or maybe most, I did not keep track) of them last had activity years ago.
As an example this question was asked and last active over 6.5 years ago, Highly Active does not describe it in my book.

Now I do vaguely recall seeing questions that were protected/locked to prevent the same activity that this header claims to prevent.

Maybe it's been brought up before, but I tried 2 or 3 different subjects and did not see it pop up.

Just wanted to voice my concern.

Answer 1

The "highly active" term has now replaced the "protected" term, but the principle is the same: these are questions that have been specifically marked by moderators to prevent new users with very low reputation to answer.

It is typically used for questions that get viral (due to the Hot Network Question list, or some tweet - hence "highly active"), so that people that aren't quite aware of the site rules don't pile in just to answer things like "great question", or "I experience this too", or some other kind of noise or spam.

Recently, the post notices for closed/protected/locked/deleted posts have been refactored by the SE team. So now, the "protected" term has been deprecated in favor of "highly active". It is possible that these questions aren't actually highly active anymore, but at some point, they have been. And they are still in that state where low rep users can't answer.

There is more details about the significance of this statuts on the main meta: What is a “protected” or "highly active" question?

Also, see this post about the refactoring of post notices: New Post Notices are live network-wide. And have a look at pkamb's answer there, which summarizes pretty well how this new "highly active" notice is, indeed, very misleading.