I understand that perhaps they _could_ ask the VPN provider to give logs (depending on the provider, if they keep logs or not). But that would not work for the algorithms used to target you as an individual.
Could someone please explain that to me? :-)
First is cookies. Say you log in to Facebook with your browser from your own IP address and a hour later you fire up VPN to browse the web. One of the websites you load has Facebook's tracking pixel and - unless you cleared your cookies - boom: Facebook knows you have visited that site.
Even if you clear your cookies, you may have some long-living stuff (like Flash cookies etc) that can be used to track your browser.
And even if you clear everything or use incognito, sites can use some clever heuristics (CPU power, enabled plugins, timezone, browser version, webrtc, etc.) to track your browsing and to match that it's you.
The last part of which you wrote is incredibly interesting. I had no idea they could find out the CPU power or the enabled plugins.
Though, to be fair, I think I'd fall in a pretty large pond to match. And either way, that information does not seem very useful (to me) for targetted advertisements.
Thank you for your answer :-)