Using a mixer isn't illegal. Mixing coins isn't illegal. Advertising a mixer isn't illegal. Hacking, scamming, or stealing money from people is illegal. Trying to hide the traces and history of illegally obtained coins isn't allowed, regardless if it's with a mixer, coinjoining, or any other techniques. Even if you get paid for services you provided with illegally obtained funds, it isn't your fault, unless you knew about it and agreed to receive such coins. You can literally have money in your pocket right now that has the worst kind of history you can imagine.

Regarding the data. Using mixers through clearnet sites was never recommended. That should always be directed through TOR.
Like I said, the use of a mixer isn't illegal. The only people who need to be worried are those who mixed coins that originate from hacks or other illegal sources.