The law is clear in circumstances where an airline cancels a flight - for whatever reason - that all passengers booked on that flight are entitled to a full cash refund within 7 days. That provision is set out in EU Regulation 261 (2004). Notwithstanding the contraints arising from the COVID pandemic, a small number of flights are continuing to be operated. Where a flight takes place there is nothing in the law that entitles a passenger to a refund from an airline.
My understanding is that the current practice of the two main Irish airlines serving the Irish market is to offer the opportunity to rebook a flight for later in the year or receive a voucher. I am not aware that people are losing out entirely in these circumstances.