@jnd2546 

It's the difference between Advance Payment, and Actual Eligibility.

The payouts are based on projections from the most recent tax forms on hand at that time. The benefits are reconciled to Actuals on the 2021 tax return. That's because life changes.

"If you were claimed as a dependent on someone else’s tax return for 2020, you were not eligible for the third-round Economic Impact Payment. If no one can claim you as a dependent for 2021 and you are otherwise eligible, you can claim the 2021 Recovery Rebate Credit, and must file a 2021 tax return to claim the credit."

Not being eligible for the payment in 2021 is not the same as being eligible for the funds based on the 2021 tax return.