In strategy games this is called "smurfing", that is playing nearly-sure-win games with players way below your own skill level.
When I first played I won 6 out of the first 7 leagues. I've even won the first league starting at day 4 which says how easy it was. I'm still f2p to this day and never farmed any tokens.

Yet, this game has no mechanics to prevent smurfing.

The main culprit is being that there is no advantage playing a higher league compared to a lower one, but the higher level you are the more disadvantage you get (stronger opponents, relatively lower competition prizes, smaller market). This is very different compared to most games with player level systems, which the higher level you achieve usually means you are stronger than the lower levels in every way.

This result in zero incentive to level up at all.