Hi Megan,
Yep unfortunately this is normal. It’s an anti-money laundering process that casinos implement – you basically have to withdraw to a card to account for the amount deposited.
If it’s expired, you just have to request that card to be removed. They may ask for proof of this from your bank.
Once this is removed you should be able to withdraw to your new card as normal.
P.s. congrats on your huge win – going to be a nice Christmas for you! 🙂