This suit seems to just be vaguely, “30% is too high”, along with requiring that DLC for a game bought on Steam also be bought on Steam, it was the Wolfire case back in 2021 that alleged they’re not allowed to sell their game for cheaper on other platforms
This is true and public knowledge though as I said (details seen here in the “Steam Key Rules and Guidelines” section), if anything Valve is giving devs a lot of leeway by allowing them to do that at all, not only are they giving up their 30% cut but are also then distributing and committing to updating those copies of the game for free