I don't think there's enough evidence to just say a scam. There are dozens of stocks outside of Sistemcoin in the same way trying to emerge in the rankings with fake volumes. But, if you ask, I certainly can say that I dont trust them and I didnt do anything in this exchange and I will not in the future!
we post details about exchanges
you can find details here
https://cryptomaa.com/exchange/you can find fake exchanges here
Based on what you these exchanges have fake volume? I see that you have binance, bitfinex, bittrex and many known exchanges.
I find quite weird that they are faking trading volume.