Yes --- amending 2020 is the only way to resolve those issues. The recovery rebate credit is in Federal Review. There were two stimulus checks for 2020----the first one was $1200 per adult and $500 per dependent child under 17; the 2nd one was $600 per person.
If you paid tax on unemployment received in 2020 and filed before the tax law changed you can seek a refund of the tax that you paid on the first $10,200 of unemployment.