@dotterel - the IRS works on a 'one sided coin'.
Once three tax years go by, you have to further right to a refund, but if the amendment would require you to pay more tax (not the issue here), you still owe it.
normally.....
for the 2018 tax year, the right to amend and get a refund expired on April 15, 2022
for the 2019 tax year, the right to amend and get a refund expires on July 15, 2023.
