You are right, if the top casino will notify the update of the terms and conditions with several strategies so that all users are aware of the updated TOS of the casino that has been changed or has been added other points, the most effective way is to announce in the pop-up information after the user has logged in to his account and the casino must send a notification to the user's email so that changes to the TOS are not debated in the future, but if the casino fails to change the TOS to the detriment of gamblers and the casino will not publish information on changes to users so that the casino blames users for ignoring the TOS.
There's a usual line related to terms and conditions,
"some terms might be changed or modified without noticing users".
Whether the casino should notify the users or not, really depends on users on approaching the site if something unusual happened. We don't really know what will be the scenario if these casinos began questioning us. We should participate lightly and calmly to what they asked for and just follow what they want us to do.
In case we already give everything and still no sign from them of being a positive, we can act now.