The turbotax program is deducting $600 out of my refund because of the stimulus. IRS told me in no way should it affect my return. That Turbotax is in error, why?

Every year I ALWAYS get over $1,000 back from my taxes. When the program asks how much stimulus i received and I enter the amount in drops by exactly$600. As I have stated, I contacted the IRS on this matter and they assured me that the tax preparation service (Turbotax) I am using is in error. What is the story here?