Gambling sites won't be able to directly detect if you're using a VPN, but when they see that you're logging into your account from different locations at different times, they can guess that you're probably using a VPN. Because without a VPN, an account can never be logged in from different locations at different times. But if you don't gamble with large amounts of money and it doesn't come under the kyc verification requirement, chances of your account having problems are very low. Because all the sites I used were VPN Friendly.  Because I accessed those sites using vpn.  This is because gambling sites are banned in my country which is why I have to use a VPN