> The main solutions we have today are IP ban + VPN blocking using a database of known VPN subnets and adding them all to the firewall, and a similar fingerprinting technique which scans their folder structure of certain system folders.
No. VPN blocking is useless to stop malicious actors as most residential connections have DHCP and VPN subnets are added and removed somewhat frequently, it's not that hard to find a "undocumented" one. It also completely excluds anyone using a VPN for non-malicous purposes.
Scanning files and folders is just ridiculous, not only an incredible invasion of privacy, but also trivial to work around.