This is a very old source, from what I hear this leaked years ago, but note this is all based on the initial contract. Kind of explains why SM works their groups to the bone during years 1-6 then neglects them for the final 3-4, and doesn't like to send them on tours outside Korea.
https://www.reddit.com/r/kpop/…/#:~:text=Musicians%20don't%20make%20much,most%20cash%20for%20these%20labels.
Edit - if you have chrome, here is the page it likely came from (note you'll have to add the second n and remove the space) https://pan .nate.com/talk/330911705
I remember reading that and there were so many people that doubted the authenticity of it