My LLM Bill Kept Growing, but User Traffic Didn’t

My request count looked normal. Traffic was mostly flat. There was no sudden wave of new users, no runaway background job, and no obvious model upgrade hiding in a deployment. But the LLM bill kept climbing. My first instinct was to look for the usual suspects: a pricing change, an expensive model accidentally pushed to production, or someone hammering an endpoint. None of those explanations held up. The problem was simpler: I was measuring requests, while the provider was charging me for…