Never mixer huge BTC, always use Tor, and make sure you use 3 direct mixing methods (decentralized mixing should be included).
Can you talk a little more about this? Or in what topic it is possible to find out?
This is issue was discussed some years ago and based on the research was done by reputable members of the forum that there's a chance for flaws when mixing a huge number of BTC like 500 at once through an external mixing service.
Having said that, when you mix through Bitcoin tumblers, you're trusting them not to keep logs this is the reason why it is good to use different tumblers when anonymity is a top priority. After you use Bitcoin tumbler, make use of a privacy wallet like Wasabi and no KYC p2p exchange.