How to deal with cashback?

Hi,
I was wondering how to deal with cashback?
Shall it be considered as “free”, like and airdrop or a reward?
Or would it be possible to consider them as a fiat to crypto transaction?

I mean : in a similar way that crypto credit card do a crypto to fiat transaction when you use it, it may be considered cashback is in fiat and then converted to bnb, cro etc ?