The flight was cancelled: am I entitled to a voucher or a refund?

It depends on where you are and which airline you're talking about, but generally in Europe you have well-defined rights under EU regulation 261/2004. If your flight was cancelled, you can claim either a full refund of your ticket or an alternative flight to the same destination. It's not like the airline chooses for you: the choice is yours. A voucher isn't automatically mandatory, even though a lot of airlines are offering it now to avoid refunding cash. If they offer you only a voucher and you'd prefer your money back, you can refuse and claim a real refund. Just watch out because a lot of airlines are pretty pushy with vouchers, especially post-pandemic.

What you actually need to do: contact the airline by emailing them (better than calling, that way you have a record) and explicitly ask for a cash refund according to regulation 261/2004. If you're in Italy or the EU, this rule protects you. They're obligated to refund within a certain timeframe. If they give you the runaround, you can resort to online dispute platforms or reach out to the competent authority in your country (in Italy that would be Enac). I've never had to deal with it for work, but I know people who had similar issues and in the end with the right documentation they sorted it out.