It's fairly common with serverless functions - folks will start a project on serverless, expecting very little traffic.

Eventually, they get lucky, and their Lambda functions are running non-stop, incurring a fairly large premium over a normal constantly running VM.

I managed to do this with my side project (AWS bill in the several hundred dollars per month range), I wrote about it here: https://onlineornot.com/on-moving-million-uptime-checks-onto...