Sometimes some exchanges Don't allow founds from different gambling site and they postponed withdrawal and deposit. Exchanges have some regulations and rules where exchanges don't permit gambling fund and liquidities.
Exchanges that are mandated or registered in a country which prohibits gambling have these rules to not accept transactions of funds came from gambling. So there is a need to be careful on reading TOS or the sites rules and law to know whether were on a right track especially if we needed the money since it can cause close account or postponement. What worst is if they find it out later when you already saved a lot in that exchanged.
I think most exchange that has implement of KYC/AML implementation is a part of them not accepting fund that comes from the gambling.
That's what exactly right, the best thing to do before making such a transaction is always read the terms and conditions to avoid your account becomes lock or freeze by them.
Instead, why not send it first from your clean wallet from a gambling site and then send it to the exchange platform that you have used. There will be an always solution for this if we really want to.