How do you square "complete privacy" with the fact that you're authenticating to these VPNs with a persistent username or other credential and are then sending traffic through them, both from an IP address that might identify you, and to services that you authenticate against?

Best case, the VPN learns your residential IP and the names of every HTTPS host you connect to (if not your entire DNS traffic as well); worst case, they collude with any of the services you use (or some ad tracker they embed) and persistently deanonymize your account.

VPNs are structurally not great for privacy.