PC game is totally unplayable

I bought the game 2 days ago, and i've been able to play with no issues for the first 24hrs. But since afternoon, the game has begun unplayable: when i start a rivals game, i experience a terrible input lag (like 3-4 seconds of delay), making impossible to play at all. And no, it's not a connection issue or a hardware issue: i'm playing with ethernet and my PC satisfies every specs request.  I spent 50€ to buy the game, and after just 24hrs i'm regretting the decision. PC players are treated like garbage every single year. Please solve this problem!