Were you looking for warning like “Google prevented a suspicious attempt to sign in to your account using your password.”?

Google and many websites track user logins with IP addresses. So frequently changing or switching on and off VPN service may result in such a warning. In the real world, Google and such websites consider that an IP (and so location) which is far from the user’s usual last set of IPs (i.e. locations) may be a login attempt by a hacker, located in other country or so.

If you are sure that the attempt was not by a hacker (and was the IP provided by the VPN), you can ignore such a warning.