2021 Covid Stimulus Check - 2019 vs 2020 AGI

Can Anyone address ramifications of round 3 stimulus check where 2019 AGI is within max limits for family but AGI for 2020 filing won't? We qualified for/received both full initial rounds based on 2018/2019 filed AGI of married filing jointly with two children. Haven't filed our 2020 taxes, as yet, but our 2020 AGI increased to $159,000 which, apparently, is in the new lowered phase out range.

 

Assuming IRS deposits the full round 3 amounts of $5,600 based on our 2019 AGI before we file for 2020, what ramifications would there be of accepting the round 3 stimulus based on 2019 AGI and then filing 2020 with an AGI within the phase out interval?