What a bad timing indeed. Honestly, there was no problem at all on the side of OP, regardless of whether he was using a casino address or from any wallet since he always checked the deposit address no matter what when doing a deposit transaction.

It's just that when the expected funds arrived that deposit address got updated.

A bad timing and the site should not keep OP hanging on that problem. Usually, even if it was sent to the former address, the funds should still be received by OP since there should be at least a period before the former address will be completely unlinked to the OP's deposit address on that platform.