" I issue invoices that with Amazon's fees"

You issue invoices? What for and to whom do you send these?

"Where can I find the exact fees that Amazon deducts?"

You can find these fees ONLY if you don't own a national VAT number and therefore Amazon is collecting VAT from you and sending these amounts to your country.

If you put your VAT number in your Amazon settings, you will not get such an invoice because in fact you don't "pay" the fees but Amazon will deduct it from your sales. The amounts Amazon pays you are "NET" earnings/proceeds. That net amount is your earning, fees deducted, not a virtual amount the customer is paying to Amazon. Explain this to your accountant.