There used to be some kind of fees on P2P trade when the whole feature was still new on CEX until Binance decided to make it zero fees p2p to attract vendors from other CEX to their marketplace. Initially, Binance was always charging fees but removed them as the exchange grew larger. That move alone forced other exchanges to remove fees from their p2p to compete with Binance. I believe Bitget has reinstated fees to its p2p marketplace now that Binance is no longer active. Bitget and Bybit are currently the exchanges with the biggest p2p trading volume, and they can extort vendors as much as they want because other exchanges are not in competition.
If it was service tax or VAT tax to the Nigeria government they would've send a notice about it just like Kucoin did but it's not. 0.5% on sell order is too much. Imo