Hi,
I have the same issue. Previously I did not pay attention to these emails as my girlfriend sometimes used the phantom account because it did not required a password, but now that she uses the main account as well these emails are still coming in. Both today and yesterday I received these suspicious activity emails while I'm 100% sure that only the main account was logged in.
I hope this isn't some kind of hack where the phantom account is activated when the PC is turned on?
Best regards,
Erwin