Stakes can ask for KYC any time they want. So, be ready to Submit KYC if they ask you to verify. I have been there for a long time, yet I did not KYCed there. They did not ask me, maybe because of my gambling habit. It depends on various factors, including what games you are playing, on which market you place your bets, and how much the amount is. If you place bets in Sportsbetting and play 3rd party games, you will likely trigger KYC. Also, Sometimes they ask for KYC if they are suspicious of your activity like arbitrage betting, Random IP change etc etc.