As far as I can remember, it was not mandatory when they started, but like a year ago, then started a Level 1 verification. I know this because I used to play slots on Roobet during my downtime on the pandemic. However, I would be honest, that I was completely caught off guard by the Level 1 verification so I haven't used their sites for a long time now.
I will reckon that it will be the case for new registered users. They have implemented it already so I will assumed that they will continue to mandate it.
Yeah it wasn't mandatory at all, but I am guessing that they grew too big, because when they first started they didn't had this type of problems and money, but right now they are doing millions of dollars. Which means that, in order for them to claim that to their bank accounts, they need to make the business as legit as it gets.
I do not where they live, but let's assume a random nation like Germany, if you are a German, and you own a company in Bahamas or Costa Rica or whatever, and then send that money to your German bank, there could be problems. But if you register it like Malta or something and ask KYC and legit, then you can send that money without an issue. When you make 10k a month, you can spend that as crypto, but when that is 1 million a month, you need to become a bit more legit.