Sportbets.io is not listed among. I withdrew bitcoin on Sportsbet.io recently and I withdrew it using lightning network. I hope other well reputed gambling site like Stake will support lightning network soon. The mempool is not that congested recently. If the mempool is congested, I can decide to use USDT on Tron or BSC network on Stake.com.
Yeah, at least, for some time now, the bitcoin network has been relatively free off congestion and both transactions confirmation cost, as well as confirmation time has also been relatively good.
But this does not mean that the issue with the network's scalability is solved, I am personally assuming or predicting rather; that as we enter the coming bull run, the network may face another congestion, since that is mostly the time when alot of people are moving bitcoin around, developers may also want to start some new projects on the bitcoin blockchain so as to benefit from the bull run.
So, I personally support the expansion of the lightening network, big casinos like Stake should already have this future by now, I wonder what is keeping them from implementing it as the top crypto casino.