Why is the assets in “OTC Trading Account Total Asset Converting” seems like became less after converting to fiat currency?

This is due to the differences between the conversion price and the actual price when you bought the currency, but the amount of your digital asset didn’t decrease.

For Example:

If users had bought 1000 USDT in Hotcoin.top OTC market, and the unit price of USDT is 6.5 dollars, the user pay for 6500 dollars, and the currently USDT reference price is 6408, then the converting total asset of OTC account is 6480 dollars, This doesn’t means a reduce of your digital asset since the amount will still be 1000 USDT, the situation is due to the reference price makes your converting total asset seems like reduce.