Your phone always says "Google located it": is this the Google "Find My Device" locating it? I ask because if it is that would definitely mean that someone has access to your Google account (and perhaps is too ignorant to realise that it now notifies you on the phone).
If you have to secure your Google account, do not use a potentially compromised phone to do so. Use a computer.
Most of the other stuff I don't know what that means: any "hack" that produced those symptoms would be completely incompetent. But if you want to be sure I'd back up anything truly important (like contacts, photos, etc), remove the Google account from your phone, secure the Google account (change passwords, enable 2-factor authentication, check what devices have been used to access it and de-authorise any you don't recognise) then factory reset the phone. Do not just restore all of your apps and their data, since if there's any malware there you risk restoring that too - be selective.
The reason I said to remove the Google account before resetting is that if you change the password and then reset the device (or do it in the other order) the "factor reset protection" system is likely to conclude the phone is stolen and lock you out for a few days (because that's a common pattern with stolen devices: the thief resets the phone while the owner changes the password, so the 2 of those happening within a shortish period of time is a red flag).
