Sorry, but this is not correct. There are a few casinos that are VPN-friendly and that state clearly in their ToS that they allow the use of VPNs.
Regardless of whether the casino is VPN-friendly or not, the most important thing here is why you are using a VPN.
Most casinos won’t care about it if they know you didn’t do anything against their ToS, but they (including VPN-friendly casinos) will ban your account and confiscate your balance if they suspect you are using a VPN to bypass any of their restrictions or to try to cheat them.
The issue with (free) VPNs is that the IP is basically shared. Although it might be uncommon for the same two (or more) users to be using the same VPN service in the same casino, it's not an impossible scenario and could potentially explain why some users might be accused of multi-accounting, even in VPN-friendly casinos. The safest option would be a subscription, yearly packages don't cost too much, and it's worth the money if you want some peace of mind. I personally use a private DNS (Cloudflare), because most cryptocurrency casinos are blocked here.