Imagine authorities running a mixer to identify their so called criminals, that will be a disaster to any users who fan of using mixers.
There is no need to imagine, I am sure some mixers are actually operated by government agencies in a same way like they are operating Tor nodes.
You can browse the internet or darkweb with Tor browser thinking you are safe, but your activity is actually being recorded by this nodes.
I would go only with reputable and reliable mixers.
What I actually talking is about the idea what I mentioned because there will be no one in their right mind with an anonymous ideology who will use a "legal" crypto or bitcoin mixer unless they accept those huge risks you have mentioned.
Totally wrong thinking caused by government brainwashing.
People are not using mixers because they are doing anything illegal, but because they want to preserve their privacy and not expose their all history of transactions.
It's much bigger risk to use only legal centralized exchange, kyc verification and do no-mixing of coins.