The biggest scam is with Browser VPN, they are simply proxies, good to watch country restricted movies but not for more. They don’t protect privacy, because they only can create the tunnel, after the browser is already connected to your ISP server. Bad in countries with dictatorship or teocracies with controlled servers, there only steganographic methods can help in comunications (Hidden messages in Photos, music, or even innocent text files)
But normally 100% privacy isn’t possible, almost every actuation online can be tracked. You can only avoid the worst with your shitty PC against the server and AI power of big companies, goverments and secret services with their hacker squads. Tey can spy other goverments, they are swallowing this little geeks with their laptop and VPN in a breaktime if needed (China even employ savants (isle gifted autistic people) as hackers in their secret services)
I use DNScrypt and Quad9 DNS