Unsual token cost for flash 2.5 image api call

I just built an image remix app via AI Studio this week, and the app worked very well. However, I noticed that the token cost of my app is surprisingly high compared to the official pricing policy (30 USD / 1 million tokens). I was charged 3.54 USD for 3870 tokens, that’s around 900 USD / 1 million tokens. I wonder if there is something wrong with my understanding of the pricing policy, or if anyone has experienced such an unusual token cost as well?