I doubt they are doing it. You just have to get on a VPN to and see yourself being flooded with captchas despite browsing the web like a normal human and solving dozens of captchas along the way.
replyI guess that raises the bot score given that the vpn IP is a data Center IP and thus in a lot of ban lists
replyAlso some of the free VPN apps support themselves by proxying this kind of traffic:
replyhttps://www.kaspersky.com/blog/what-is-wrong-with-free-vpn-s...
Which also involves detecting entropy across sites I guess
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