Why is a smaller amount paid?

Earlier, when ordering $ 2, I was paid $ 2! The last time (Aug 19, 2018) ordered a withdrawal, as usual $ 2, but I was paid $ 1.6. On the output page nothing has changed, as it was and remains - "Withdraw fee: 0% + $ 0.000". Why was I paid a smaller amount? Is that a mistake?

It depends of your ROI, if you are above 100% , some money will go to purchase balance.

I made it more clear: http://prntscr.com/kksn24

And where it is possible to read (or, if it is not difficult for you, tell us) how this ROI is considered.

http://www.goldenclix.com/index.php?view=faq