> Long-running tasks like batch mode completions and agent sessions may incur overages beyond your project spend cap.
> Billing data processing times can be delayed in AI Studio, up to around 10 minutes. You may experience overages beyond your project cap if billing data hasn't processed before more charges are accrued.
https://ai.google.dev/gemini-api/docs/billing#project-spend-...
That's a soft cap, not a hard cap