https://www.polygon.com/2018/12/3/18123649/valve-steam-revenue-sharing

Valve used to take a 30-percent cut of all the revenue that games brought in through Steam, the company’s popular storefront for PC games and software. This didn’t always sit well with developers, who sometimes argued that Valve wasn’t doing enough to earn that large of a cut.

Valve has now announced that it will take a smaller percent of a game’s revenue once it hits certain sales milestones.