Flight booking hidden charges

I recently booked a flight ticket via GotoGate and the total amount displayed was 37.600 OMR. This was including debit card charges.

The money deducted from my amount however amounted to 39.600 OMR. And also the debit amount was in USD. Around 97 USD. It's all very confusing since 97 USD is 37 OMR.

Anyone knows anything about this? It's only a couple rials so it's not an issue, but I just wanted to know what actually happened.