I was targeted by this exact same attack several months ago. It sounded incredibly real, the emails looked legit, down the domains, Google even has a process for this exact scenario. The only thing that tipped me off is that they sent a login request to my phone. Nothing about the login request seemed off- it even originated from a Mountain View IP. But it was the fact they had sent me a login request which prompted me to drill the voice on why they needed a login request instead of some other form of verification. The disembodied voice soon became agitated and eventually told me that I should expect to lose access to my Google account soon since I hadn't complied with their request.

It was only after I checked Twitter that I saw Garry Tan's callout of the exact same scam. After experiencing it myself, I wouldn't fault anyone who fell for it. The only other tip-off was that the voice was pretty monotone and unemotional, but that only appears obvious in hindsight, not in the moment where you're slightly panicking that someone might be trying to claim access to your account.