Yeah I think it was publicised a few years ago that Rockstar had a special deal for Grand Theft Auto V at least. It may have been all developers get reduced fees at certain sales tiers but I don't remember the exact details.

It is public knowledge that fee drops to 25% after $10,000,000 and down to 20% after $50,000,000 in game gross revenue.

Pretty well known that they and others dont pay 30% after some number in sales.