Why did you send your coins directly from casino to mixer? you can use non custodial wallet first.
Based on my experience, the casino neither block my withdrawal or account, as long as you've submit your KYC. Usually the casino will flag your account if you receive/send the coins related to mixing service.
2. use a trusted mixer that has good aml score and clean coins
My question, how to know the mixer has a good AML score and clean coins?
You need to check first. Mix your coins and use a AML core checker or read reviews about the coins they send.