Confusion about AI Studio prepaid wallet and Gemini TTS billing

I recently added 1000 to my Google AI Studio prepaid wallet and linked it to an existing Google Cloud Billing account.

I can see that the amount was deducted from my prepaid wallet, but I also received a Google Cloud billing notification showing a total amount that includes my Gemini usage, including Gemini Text-to-Speech charges.

This has left me a little confused about whether I am being double-charged, or whether the Google Cloud billing amount is simply showing my total usage before the prepaid wallet credits are applied.

How can I verify the exact amount deducted from my wallet, the credits applied to my Cloud Billing account, and the final amount I will actually be charged?

I would appreciate some clarification on how the prepaid wallet and Google Cloud billing work together.

Video for reference: Screen Recording 2026-09-12 160653.mp4 | Media2URL