MixTum.io is a one-of-a-kind bitcoin mixer built on Jambler.io platform and launched in August, 2018. While mixing BTC, MixTum.io does not shuffle available funds in one or multiple pots, but exchanges incoming bitcoins with coins purchased from investors -  cryptocurrency stock exchanges.

I have a question to ask because I am new to using mixtum.io . Originally how bitcoin mixing work is that funds(bitcoin) are intermixed amongst the list of available pots which causes a blockage towards anyone trying to trace transactions.

But if I am correct Mixtum.io doesn't work that way only swaps the expected funds (Bitcoin) with coins bought by investors.

My questions are:
1. How does this process work?
2. Are the investors those who invest in mixtum.io /Jambler.oi or what platforms are these investors from?
3. What makes this process untraceable, support anonymity and lastly what are other downsides one should be aware of ?