neftv How is it known by that site that it would be a VPNserver.
Look up what a Regional Internet Registry is. Put simply, the RIR is supposed to administer who authoritatively owns an IP block, 8.0.0.0/8 for instance.
Your VPN provider needs an IP block and gets a smaller subnet of 8.0.0.0/24. Said company is supposed to provide registration details identifying themselves as owners of that block, along with contact details.
Anyone can query the RIR database and backtrack that 8.0.0.17 belongs to your VPN provider.
HTH
Regards