I just amended my taxes and it asked if I received stimulus. I did with my refund of 2020 and answered with a yes. But now that I’ve finished it says I owe the 1800, why?

Sometimes you have to "lie" on an amendment to get to the true answer.  If checking Yes, makes you owe the stimulus payment back, then don't check yes.  This is not being deceitful, it is doing what it takes to make the software work for you.  You know you do not owe the stimulus money, so don't submit a return showing that you do.

What ???

if you amend, you must answer for stimulus the same way you answered on 1040.

Otherwise, you will end up paying back the Rebate Credit.

This should be obvious.