Edit: it's possible that this is an issue of semantics. My cards have been debit cards in every sense of the term - they are labelled as such, are linked to a specific current account, and debit it immediately - but I don't think any of mine have actually said Visa/Mastercard Debit. So strictly speaking they may be implemented as a sort of instant-clearing credit card - essentially shimming debit onto credit infra. I don't know a whole lot about the finance industry or its tech, so if anyone can chip in please do
Edit 2: Ah, my current one does have "debit" in the MC hologram on the back