They have a number of blockchain transaction tracing tools at their disposal, so it's likely that they were able to trace the transactions. The other mistake you did was to reuse the address. If you are privacy conscious, once you reuse an address, the privacy level drops, and you made the job so easy for them.
I could understand why centralised exchanges would want to keep tracks on transactions and label a certain number of it from certain addresses to be suspicious but, isn't this supposed to be obliterated by mixing services as well?
By that I mean, not having to reuse an address increases privacy level, having both ends to do this is good enough to obliterate historical data to address linking. Hence,
Is the result of transactions from @Coupable in anyway implies that, return address stays same to enable tracking?
Excellent question. This presents some of the biggest dilemmas that mixing platforms are supposed to face.