Here are the instructions from the draft 1040 for 2020: Looks like they changed their about someone who died in 2020

The economic impact
payments were based on your 2018 or
2019 tax year information. The recovery
rebate credit is figured like the economic
impact payments except that the credit
eligibility and the credit amount are
based on your 2020 tax year information.

Generally, you are eligible to claim the recovery rebate credit if in 2020 you
were a U.S. citizen or U.S. resident alien, weren't a dependent of another taxpayer, and have a valid social security
number. This includes someone who
died in 2020, if you are preparing a return for that person. Use the Recovery
Rebate Credit Worksheet to figure the
credit,