Regulators often flag mixer-related addresses as “high risk” or even “suspicious.” So if you withdraw your winnings to a mixer, it could backfire with the following problem.
First thing, why in the name of God would you do that?
The main problem is that withdrawals can be delayed and the address will expire in some mixers even as quickly as 24 hours, some in 72. If the casino takes longer than that to process it, your money is gone.
Then, it offers no advantage. You can simply withdraw to a different fresh address every time and then send those to the mixer address. Since the mixer itself will have one collection transaction for your funds, there will be at least three hops between the withdrawals and the actual mixing process. That is pretty hard for anyone to keep track of, especially if you use that address from time to time to deposit to an instant exchange or something like that.