This is a question I could not answer by googling so far. I was experimenting with Vpnbook VPN. The question may apply to any freevpn with public credentials.
Here goes: when I connect to one of their VPN servers, my ISP knows where I connect to, the free VPN server. Knowing that, they can easily identify that server as a vpnbook server, then go fetch the username and password credentials which are made public on the www.vpnbook.com web page. Then with this information, they should be able to decrypt my brownsing if they want to.
Is this true? Ron