Does it depend on that? It will affect the cost to DoorDash, but if the premise of the lawsuit is unfairness of price discrimination based on device operating system, then I don't see how it's relevant to the end customer that DoorDash pays a different cost for their transaction.
That said, I'm personally skeptical that the premise is even defendable in the first place. Operating system is not a protected class and so I don't see any legal basis for why a company couldn't price discriminate based on it.
As a shopkeeper, I can offer a discount for cash rather than credit card. Why couldn't I offer a similar discount for some other device characteristic, especially if there's a direct line between that choice and the economics to me?
If doordash says we charge a X% fee but then Apple charges Y% on top while android charges no fee then logically it should be higher on Apple. If doordash is saying we charge a higher fee on Apple because Apple users are generally wealthier, thats pretty discriminatory.
That said, I'm personally skeptical that the premise is even defendable in the first place. Operating system is not a protected class and so I don't see any legal basis for why a company couldn't price discriminate based on it.