Changing of terms and conditions without notifying the users or gamblers is normal with online gambling websites?
No, it's not normal and not acceptable.
Any reputable casino or any other service provider must inform its users about any updates in their terms of service. They must also mention when the last time their terms were updated. Besides new terms and rules should not have a retroactive effect. Any company that doesn't do this does not respect its customers and it should be avoided at all costs.
Chips.gg is a good example of this topic. Chips is one of the crypto casinos that changed their ToS without any notice. They did it more than once as I remember. Apart from being very unprofessional, we have to ask ourselves if they are ready to do that what could they do next?
Well, Betnomi didn't wake up from maintenance mode, maybe the same thing will happen with Chips now.