I tried this service today to mix around 50 USD.
I sent to the wallet provided and once deposited, I selected to withdraw all.
I imported the keys and I get around 48 USD, meaning I lost around 4% of the money sent.
So I paid 4% FEES

On your site, you are advertising your fees are "Pay what you want" also referred as "value-for-value".

So is it SCAM or how do you explain these fees please?