I had a similar experience with my revolut card. I was purchasing from a UK supplier, and had the funds in my GBP account. The transaction kept trying to take the money from my Euro account (which failed as I didn't have enough funds in it). On investigation, I found that some suppliers use a retail (possibly 3rd party) visa machine, that will default to charging in Euro, depending on the card. Or possibly the retailer, knowing you are in Ireland, is choosing Euro as the currency. So the problem may be with the retailer, not Paypal.