Hey TouchedMoon. I've seen the same thing happening to my projects, over a third of our traffic comes from "https://itch.io/".
The explanation I've found is that, if you're logged in, Itch can display on its main page game recommendations tailored to you, based on what you played, rated and who you follow. If I had to make a guess, I'd say Itch is showing your game to people who have played and rated racing/simulation games highly.