By using a VPN you are essentially routing your internet traffic through another computer and another ISP. So you have one of the VPN provider’s IP addresses. So what they have to do is find out which IP addresses are used by VPNs and block those. It’s very hard, but for the biggest companies somewhat doable.

For all the hate that the EU gets, I really appreciate that they won’t bend over for corporate overlords when in comes to privacy.