Yes, they do remain in that UY - but in most circumstances you will have used them. They won't become distressed unless you cancel - or the resorts are closed, as they were earlier this year.
I think the folks who lost the most points due to COVID were those who had 2018 points banked into their 2019 UY and applied to reservations affected by COVID. Those 2018 points were extended somewhat but have to be used by November 30 of this year. If people had instead borrowed 2020 points into 2019 UY for those same reservations,
DVC would have allowed them to "unborrow" those points and return them to 2020 UY, and depending on the UY banking window, some people were able to bank their 2019 points into 2020 as well.