It's not broken, it's working exactly as intended, this way the rewards will trend towards those who have spent the most money, You're playing a p2w browser game. The whales (who otherwise have empty, meaningless lives) get to feel superior while normal people feel enticed to spend money to gain an advantage.

It's the same when they introduced cross server matsuri, people complained then too and nothing has been changed, because it's the perfect system, help the whales feel like they have finally accomplished something in life while trying to entice other people to spend.

Rewards trend towards the top, this is true in any single aspect of this game. Anything that Oasis can do to facilitate that is intentional, because there is no game, it's just a skinner box designed to alleviate whales from their "hard earned" money (hard earned usually meaning their parents money, like the guy on my servers 80k odd power where the guy in 2nd place has like 50k, he's not shy about being a dumb rich kid, he actively claims this without any sense of shame).