What are the standard terms for Apple Arcade developer monetization?

I can't share specifics, but what I've heard is this:

• There is a "formula" for calculating developer payouts, but it is very convoluted and based on a number of engagement metrics that are largely outside of the developer's control -- a dev can't eg. run marketing for their app within AA to drive engagement;
• Because of this, most developers are trying to negotiate for a very large minimum guarantee -- enough to justify moving to Apple Arcade even if they don't ultimately make much money via that payout system.

This is similar to how authors negotiate royalty advances with publishers in book deals: get as much as you can upfront and don't plan on getting paid out in royalty fees unless your book is a massive success.