I haven't had this kind of problem but I've had Google Fi since it was project Fi around 2017. And had a yubikee on my Google account for just as long. Wonder if that's why. I do remember back in the day losing an old Verizon flip phone and buying a new one in store. They didn't properly disconnect my account from the old phone and someone was deleting messages before I could read them etc for a solid month before Verizon figured it out. But that was like 2001? Things have changed quite a lot.