There was an exploit during day one where people could TR and claim winter lanterns. The high scores were triple-completionists with capped out Reaper Points who picked up Winter lanterns and the leaderboards are claiming that they earned the last few years of progress over the single week the event's running.
You can also Triple-Ottos-Box up to 34 immediately, then run Endgame Reaper quests to farm RXP that way.
The Favor Leaderboards are also scuffed but at least the numbers seem mostly realistic. I can confirm the top three guys are playing fair (as I was grouping with the other two for the ride up), but if people actually cared about the favor leaderboards at all, it'd be beyond easy to just... double back and do favor cleanup the moment you hit cap. There's no safeties on level to farm favor, it's just a timegate check. The only thing from keeping me from going higher is that I'm not VIP and don't care enough to grab my opener to open low-heroic quests for me.
My view is that they should've added Summer leaderboards too, and just fully play into the fact that this event is a dumb joke in its entirety. It's taking itself way, way too seriously for what it actually is.
Basically, this event's leaderboards are a bad joke from day one, and shouldn't be considered anything of real value. Farm your cosmetics, get your sheet music, keep whatever keepsakes you like, and enjoy the aesthetics of the Sky Golden Mote, because that encounter is actually really cool, even if none of the other four are.