DO NOT amended your 2020 tax return for the unemployment exclusion. The IRS is going to recalculate your tax return and send you the additional refund. It might take several months to get it. There is no way to know in advance when you will get it. For details see the following IRS announcements.
IRS to recalculate taxes on unemployment benefits; refunds to start in May
IRS begins correcting tax returns for unemployment compensation income exclusion
