I just want to give a bit more background here.
What we are discovering is our users opening an old topic and then flagging it for one reason or another, only later to discover it is an old topic. As one user put it, it would be nice if there was a banner at the bottom or top of the page as you scrolled stating “This is an old topic” (see mockup from said user – thread was closed after initial complaint, so disregard the closed post in the topic)
They are replying to them, and either ignoring or not paying attention to the “Revive old Topic?” popup (which definitely shows).
Our suggestions back to them have been, look for the cold mapping (no one has realized that was happening or what it meant), click on the posts column to get the start/last response dates and times (no one knew that was possible!), and to look for the Revive suggestion, which only applies if you choose to reply (doesn’t apply to flagging).
There is an obvious gap here, as most of our users come from searches and will just enter the topic outside of the topic list (so cold mapping and the posts column modal are useless to them). We really need something on the topic itself.