This isn't correct , you get the fee back. You can see this when you click on the transaction when you log in.

It's just slightly confusing as it shows the fee as a positive number, but it has been refunded if you calculate using the exchange rate shown

So any differences were due to currency movement

Recent example:

13 MAR 20 BA.COM SWEDEN
-£51.21DOING BUSINESS AS

BA.COM
S-000 00

SWEDEN
DATE PROCESSED:

X MAR 20


FOREIGN SPEND AMOUNT
599,00 SEK

NON-STERLING TRANSACTION FEE

£1.49

EXCHANGE RATE

12.0474
So 599 / 12.0474 = 49.72 + 1.49 = 51.21