I randomly browsed leaderboard records on some maps, just to find out something weird.
Basically, full combo scores set around 2009 seems to have missing "Perfect" text, indicating that the player achieved maximum combo on a map. I'm not sure whether this is specific to only certain maps like below, as I tried to check on other maps with 2009 records and it shows the "Perfect" text properly.
Map: NicoNicoDouga - Yutaka of the Sprite Tribe [Normal], Max Combo: 84
Basically, full combo scores set around 2009 seems to have missing "Perfect" text, indicating that the player achieved maximum combo on a map. I'm not sure whether this is specific to only certain maps like below, as I tried to check on other maps with 2009 records and it shows the "Perfect" text properly.
Map: NicoNicoDouga - Yutaka of the Sprite Tribe [Normal], Max Combo: 84