30% on $10M and under.
25% on $10M to $50M.
20% on $50M+.
Game revenues follow a power law type distribution so they're hurting indies and leaving money on the table.
Valve targeted the big releases / industry players specifically because the context in which Valve added that was where all the big players were making their own store fronts: EA Original/App Ubisoft launcher, Blizzard Battle.net. And Epic Game Store, where Ubisoft (or another big player I forget) was talking about abandoning their launcher for Epic which has a lower revenue cut like ~12%. So it seemed Valve made that change to shore up keeping the big industry players releasing on Steam.