For me its not safe, but you cant do so much, also nowadays the goverment data sometimes its hacked so...... we dont know if already ou documents are in the web.
Generally there is a risk when KYC data is sent to any casino or gambling platform that have no license or comparatively weak. Because those sites can be hacked at any time. If a gambler can choose Trusted site he can send the KYC information. Because if they falsify that information, their site will be destroyed. When a gambler makes a new registration he must observe these things carefully before registration otherwise he may face danger later. Gamblers should not provide KYC data unless they can trust the site.
I mean, even if we talk about big services (not only casinos) which have been around for years, I can say that those are not completely bullet proof either. When I think on big businesses I think of Facebook, Microsoft, Apple, ect; and all of them have suffered very considerable breaches of information which have released personal information of their clients into the wild world of the internet.
Those are billionaire technological companies, so perhaps we cannot compare them to a small casino which is trying to surge among the competition, still it should makes us think on how relative cyber security is nowadays and the size or the money of a company is not a warranty or a flawless system. Just my two sats on the matter.