These instructions from the IRS:
IRS completes automatic corrections of tax year 2020 accounts related to unemployment compensation exclusion; 12 million refunds issued | Internal Revenue Service
Although as noted below, we updated our FAQs on this issue, several weeks ago, to, among other things, indicate that we had completed all adjustments, this release makes that point, more explicitly, as well as providing stats.
If you get further inquiries from readers, I would still advise checking Where’s My Refund?, first, to confirm that no unemployment-related refund was ever issued. If it was, use the Form 3911 lost refund claim procedure. If it wasn’t, file Form 1040-X.