Happening with me exactly the same way. My app uses key to let users use 2-3 free messages. But I am being charged 100s of $ monthly. Number of requests are in hundreds and customers are less then 50. Firebase analytics show API requests less than 300 a month but I am being charged for thousands of requests. I have restricted use of chat GPT4 in API but the usage on openAI platform shows Majority requests costing GPT4 rates.
Support is not helpful at all, they respond and promise to contact back after checking but they never do. Deleted keys, updated apps multiple times. But no use.
I really doubt if the keys are being stolen from my app, it must be openAI side the problem exists.
So far I had been charged 4000$ for nothing…
So frusteded at OpenAI’s whole billing and charging support team.