Below is from IR-2021-123 on 6/4/2021:
The American Rescue Plan Act of 2021 (ARPA) excluded up to $10,200 in unemployment compensation per taxpayer paid in 2020. The $10,200 is the maximum amount that can be excluded when calculating taxable income; it is not the amount of refunds.
https://www.irs.gov/newsroom/irs-sending-more-than-2-point-8-million-refunds-to-those-who-already-paid-taxes-on-2020-unemployment-compensation
Most taxpayers do not need amend their 2020 Federal tax returns, but to wait for IRS auto adjustment per the announcement.