The fraud platform that will be fined for liquidation

I made a short order with a full position of 175 dollars. When the floating loss reached 40 dollars, the margin was insufficient and the position was liquidated. The remaining 130 dollars of margin was taken by the platform. They said that this was a fine. t's really amazing in the world. Which platform didn't refund the remaining margin after a liquidation? It is really a fraud platform that OKEX occupied all the remaining margin after liquidation