USA seller First Month Selling UK Amazon - Payment doesn't make sense

Hello,

This is my first month selling on the UK, as a USA Seller, the money is converted back to my USA bank…but the math does not make sense to me at all.

Statement View:
Transfer amount scheduled to initiate on 27 Apr 2020* £438.17

I received email from Amazon… saying £398.20 will be deposited.

Variance of £39.97. Basically 10% in exchange fee?!