So the reason for your KYC verification is not the huge balance in your account but rather they are investigating if the Plinko that you use to play and won huge amount might have an error by the time you use it? This ill surely take some time because investigation like this is very sensitive to give a fair result.

How much money does your account balance still have? Is the money that you won on Plinko is still there are you already withdrew it previously before this KYC verification to your account?