In August 2017 I topped-up €100 with my Irish debit card (MasterCard) and wasn’t charged a fee but today using the same card I was charged a fee of €12.87 when I topped-up €1,000 . Why is this?
Sometimes, personal cards are recognized as commercial cards. And how fees are charged changed early 2018. Support can fix this for you.
You can also search this forum for similar cases to learn more if you want.
Who charged the fee - Revolut or the bank issuing the card?
And which of your Revolut currency ledgers did you send the money to?