Not necessarily, I mean if you buy a in-game item or currency that wouldn't be a cash advance so with this they could just say you bought $20 worth of credits and since you're buying credits that could be considered a good.
What if the site allows you to purchase a digital asset such as a CS2 skin which you can then immediately sell back to them at the same price you to get credits in your account to gamble?
If done at scale, you will get complaints/chargebacks that will trigger an audit followed by fines and/or account closure. Banks and underwriters have standard procedures in place to catch this.