I got burned by firebase in a similar way. I was using their worker queue library and found my bill for a zero user app had gone from $0 to $100. Couldn't get a

I got burned by firebase in a similar way. I was using their worker queue library and found my bill for a zero user app had gone from $0 to $100. Couldn't get a straight answer from support on why the worker queue was eating so much bandwidth. Did some experiments and learned the queue downloaded every task in the queue each time it started. The authors assured me that wasn't the case at first, but eventually acknowledged that this was exactly how it worked. Terrible experience overall, glad to have moved away from firebase.