Update 7/8/21: Deal has been extended again until December 31, 2022.
Delta has sent out an e-mail to will Delta vacation vouchers that they will be extended until December 31st, 2021:
Vouchers issued for international travel from February 25, 2020 to September 30, 2021 and domestic travel from March 1, 2020 to September 30, 2021 have now been extended through December 31, 2021.
Hat tip to 19redballoons
