please dear god correct this for tourists, they’ll have a nasty shock otherwise!
only a thousand quid
I imagine Monzo is confusingly using a comma in the European sense (where we would use a decimal point), so the rate is 166.298
Fun Facts! Decimal separator - Wikipedia
Iceland doesn’t have a fractional system as we do in the UK (well they used to but it got the axe) So in Iceland you get a lot of money but you’d be buying a £20 Frodo instead of a 20p (if we used GBP in place of kr)
It’s one of the many complexities of running a worldwide bank.
If that were true, it’s still wrong - because ISK 166.928 is £1 and not £10
Monzo is not in any way a worldwide bank. Mastercard does all of the hard work for you there.
Taking a look into this just now 
Will update ASAP.