Maybe that's how it used to work?

I'm pretty sure it all goes into one big general revenue pot now. A percentage is taken out for operating funds. The remaining are for earnings which are based on a point system. The points translate to specific earnings, but the points themselves are private. Parts of the formula are public info, though.

Reads and engagements all earn different points and vary on a number of factors. Then the points are adjusted based on follower bonus, boost bonus, and then read through rate.

https://help.medium.com/hc/en-us/articles/16030675401879-How-stories-earn-in-the-new-Partner-Program