If I were to run any public-facing protect on Google Cloud, I definitely would use a separate account, created just for that. You never knows what might happen to that account. I thought everybody does this.

I wonder how hard would it be to run a script that checks your balance e.g. every 15 minutes, and shuts down public access to your services when a certain threshold is triggered. I wonder if a ready-made service for that exists in cloud providers' offerings.