After you file

On my 2020 tax return it asks the questions about dependents and she did not qualify anymore so turbo tax marked her as no longer a dependent 

 

I would guess it’s because she is no longer in college. 

Now if the IRS went off my 2019 return it very well could be she was listed as a dependent 

 

That may be what happened. 

I’ll look at my 2018 and 2109 returns and see