Maybe you already tried but, try to talk to the customer support team of that services and see if they can do a CPFP as I see that RBF is not enabled on that tx.
I would be very surprised if that worked, but it doesn't hurt to try. I am yet to meet a knowledgeable support rep on a crypto casino that has something more than a very basic understanding of how Bitcoin and crypto works. It would require Gamdom to play around with private keys, which they might not be happy about. It's hard to get centralized exchanges to do it for the same reason. And the question is, can they even do it? They might be working with a custodial service or payment gateway on their end as well.