The first and second payments were Advances. The whole point of the 2020 tax return having the fields is that you are reconciling the reality of 2020 against any advanced payouts.

There is no splitting the qualification for the first and second payments against different income limits. They are both part of 2020 tax return computation.

In other words, if they don't qualify in 2020 due to income limitations, but they got any payment for first or second EIP, they got money they were not really entitled to.