Most of the gambling sites that require both level 0 of 1 kyc always state them clearly in the terms and conditions so that they can keep the customers informed about the casino stances on kyc and what customers can expect when dealing with the site.
There is no problem with sites that enforce KYC, at all levels, as long as they indicate the necessity of doing so on the terms of use page. The user agrees to these terms during registration for the first time.
The problem is with sites that claim that they do not enforce KYC or that they only enforce KYC level 0, and then after a while they start imposing KYC procedures. It is sufficient for it to amend the “Terms of Use” without taking into account the options of users who agreed to certain conditions for the first time. The least that can be done is to notify users sufficiently in advance before making the modification.