In the event of a long delay, the airline is required to offer its passengers care, meaning food, drinks and/or refreshments, hotel accommodation (if applicable, including transfer to the accommodation) and communication facilities.
This is irrespective of the entitlement to compensation, which is based on the time passengers lose when they are delayed. So if you received vouchers from the airline to buy refreshments or meals at the airport, this doesn’t mean you’re no longer entitled to receive financial compensation. However, if the airline offered you vouchers or a discount to be used on an entirely new trip at some point in the future, accepting this could mean you waive your rights to further compensation in some cases.