Every 2 months we reset the rankings back.
If we didn’t do this it would grow and grow and people would end up with 10k, 100k etc rank.
It’d be unfair for new players because they would have no chance to get in the top.
However you should not really mind though, everyone loses the same amount of strength.
Your skill is still the same in relation to other players.
You just get put back a few leagues because we took back the bonus you claimed every day throughout the season.
You can read all about it on the rank page.