What i check first before is decide whether or not to olay on any site to see if the casino is reputable enough to handle my KYC data and keep them private, even though we can guarantee that but we can at least be careful about the kind of casino we lodge our details on as long as it not safe then not need to play there.
That's why we have to check every casino we find so we can select it and add it to our personal list. The casino has given the rules for doing KYC and if it is a trusted casino, we can be calm about doing KYC at the casino because they will try to take good care of it.
But if it's a new site asking all its newly joined members to KYC immediately, we can skip that first. Later, after we can find reviews about the casino and it turns out that the casino is one of the people's recommendations, we can consider joining or skipping it.
By doing KYC at a trusted casino, we don't need to worry. But we must still be careful about sending personal documents and checking them first.