When you open the detail page of any of the pieces, you can see the round number where they were first seen. The leaderboard however, simply shows "Current round".
It would be nice if the leaderboard (and maybe the voting app as well) shows the actual current round number. Doing this would allow you to see which pieces in the leaderboard are from the current round, and which are from previous rounds.
In addition to this, we could also show the piece's round number in the leaderboard itself.
I attached a simple mockup, where I changed "Viewing" to "Current round", and added a section called "First seen".