Jos ah yes in this case the site may see the bunq debit card as a USA card since the PAN-range, a part of number that's on the card to identify country and bank, may have been assigned to a US bank previously before that range expired and MasterCard assigned them back to another bank, in this case bunq. I've had the same funny thing my bunq Mastercard is also seen by some sites and services as being "from the US" when it's actually Dutch. but the numbers of credit and debit cards are continually recycled as far as I know. But a lot of sites and services don't update their lists often enough. you can lookup the country for your card here: https://binlist.net by entering the first half of the creditcard no.
In my case one of my mastercards is identified as being US from Morgan Chase bank:
(the other one is correctly identified as The Netherlands but no bank either ;-(