This is the IRS online update from yesterday:

Status of Unemployment Compensation Exclusion Corrections: The IRS continues to review tax year 2020 returns and process corrections for taxpayers who paid taxes on unemployment compensation, to exclude the compensation from income if eligible. To date, the IRS has issued over 11.8 million refunds totaling $14.5 billion. The IRS is now concentrating on more complex returns. Some taxpayers will receive refunds, while others will have the overpayment applied to taxes due or other debts. The IRS will mail a letter to affected taxpayers to inform them of the corrections, generally within 30 days from when the corrections were completed. 

https://www.irs.gov/newsroom/irs-operations-during-covid-19-mission-critical-functions-continue

I have clients who filed superseding MFS returns for larger refunds based on excluding UC because income was below the cutoff amount.  IRS has processed the wife's return but did not split the withholding (community property state) so sent her a bill for $1,000 instead of a check for $3,000.  They are still working on the husband's return -- it shows up at "Where's My Refund," as still being processed.  I wonder how much longer that will be available, once 2021 return refunds start being posted.  Will they split the withholding on his return?  Wait and see.