I am a Spanish resident and received my Revolut Visa card last week (May 20th). So far, every transaction has been offered as DCC and the ATM withdrawal was being priced at €5 (Santander ATM). So it would seem that whilst the IBAN is euro, your ICA and BIN set up is probably a GBP one.
As I am sure you know this is not a great customer experience as a Spanish resident using a euro denominated account in their “home” country should never get offered DCC. Issuing the card with a Spanish ICA and BIN would solve this and I believe you planned on doing this in March, correct? I think it is vital.