It definitely wasn't a usage limit since I have fewer than 200 customers. I have a verified app, which has been up and running for almost three years now.

I suspect it happened either due to accessing my account from an unknown IP or creating and editing a Profit and Loss statement in Google Sheets, which normally shouldn't trigger any alarms, but algorithms move in mysterious ways...

accessing your account from another part of the world can trigger the kill switch.

What's baffling is that I received no communication whatsoever, not even from Google Cloud.

I already had low expectations from Google, but this is unprecedented even for them.

wtf

Is this documented somewhere? Can one notify them ahead of time?