Probably timing and amount analysis Pretty trivial for anyone monitoring the chain if they see for example 1.52334 BTC move once then shortly after another address moves the exact same amount minus fees. High likelihood it's the same user. There was a recent example of this with a Zcash whale movin...

You would want to carefully examine the history of the BTC you receive from the swap. It is challenging to vet the BTC without access to chain analysis. This could lead to issues when spending that BTC later. In the Bitcoin Fog case, the main evidence they had to imprison Roman Sterlingov was Chain ...