The ones with a number above 60k and counting is being generated by this
github.com/clarkerubber/Python-Puzzle-Creator it gets recently finished games from lichess filtered by a criteria and then searches for good puzzles.
Here's the criteria
github.com/ornicar/lila/blob/0200a19be24ceede86599908003bff096558693a/modules/game/src/main/RecentGoodGame.scala#L11-L17It tries to find rated games with at least 10 halfmoves/ply where each player has about at least 5 minutes, and prefers rating over 1900 or over 1700 if the queue is somewhat empty. If it fails it will select a random recent game instead.
I think the ones between 0 and 60k was created with this
github.com/clarkerubber/problem-creatorThere is currently no way to find out if any of your games was used