[OSButler]

Their blocking seems to be quite aggressive, as a lot of regular hosting providers even had their IP ranges blocked by them. I've been following a few forum posts where people were sharing their working VPN provider/ISP, but those were showing the same error message a few days later, so it looks like they are actively monitoring traffic and maybe even social media to block further IP ranges.

[rabidrabbit]

I was not able to test it (for example borrowing a residential IP in a different country) but I suspect they detect OpenVPN via packets inspection, like this example: "Detecting VPN (and its configuration!) and proxy users on the server side" by @ValdikSS https://medium.com/@ValdikSS/detecting-vpn-and-its-configura...