2020 is the eligible year.  If they no longer qualify as a dependent in 2020 and they didnt get the advances during 2020, then they're entitled to it on the 2020 tax return.

They can even claim the second payment for another $600.

Not Claimed and Not Qualified, are not the same.

Perhaps it would help to review what is really happening:

The funds were paid out as Advanced payment against a projection. The projection used 2018 or 2019 tax returns. But 2020 is the Actuals. You use the 2020 return to reconcile what a person is entitled to, against what they got.

If the person is not a dependent in 2020, then they would be entitled to the payment/credit as individual filers. That doesn't mean "not being claimed." It means "no longer qualifies as a dependent."

You might want to bookmark these links and read the IRS guidance.

Interactive wizards portal for determining dependency:

https://www.irs.gov/help/ita

And:

https://www.irs.gov/newsroom/economic-impact-payment-information-center-topic-a-eip-eligibility

https://www.irs.gov/coronavirus/second-eip-faqs#Eligibility

One for each EIP.

@qbteachmt  what's your count for this post ?     Nearly the same as the National Debt number ?

"what's your count for this post ?"

What I finally learned how to do is use the Macro function. Intuit provided a couple of them to us, to give us standardized and acceptable language so that we avoid snark if a person is here as a QB user or a TurboTax user. I realized I could document recurring research info and just click the "insert my macro" function for replies. So, really, I stopped counting...