So for about a few months or a month, I am not sure, but my Google account for personal stuff had been logged in only because I logged into the Gmail app.
What happens in recent versions is a pop up Safari instance (similarly used for the “Captive portals” used for WiFi hotspots) requesting for your Google login. Because this shares the same Safari instance to your app, you may not realize that other Google Apps installed (such as Maps, and others) have already logged you in. Because you logged into an indirect session on Safari, this also means that your Google searches or other Google services you use on Safari will remained logged in until you log off.
Unfortunately my searches and using YouTube had also created another Clickford account without my knowledge.
If you want to do user-blaming (“Well you should look at the TOS instead of whining”), go ahead and I will call you a wife beating rapist and child molester because you think it’s OK to take advantage of vulnerable people for your own self interest on spying users.