From the moment you open a position, Aevo constantly updates the value of your available balance using the mark price for each of your active positions (in addition to any gains or payments for funding). Whether you have options or PERPS, their value and the total value of your assets will be updated every second.

Therefore, just before the closing of one of your positions, its value will already be updated to fair market value (mark price). At the time of closing you will not see much change in your available balance, only the delta between mark price and closing price.