Ok, I did some playing around with TurboTax and I think I figured it out. It has to do with how it calculates what deduction you should take. If you skip the calculations to determine if you should itemize, that seems to cause this error. If you go into the itemized/standard deduction calculator, it will ask you to enter all of the charities that you donated to for 2020. After I did that, it stopped giving me the error.
Normally I wouldn't enter any of the information about charities that I donated to, because I never reach the standard deduction amount. In this case, TurboTax doesn't tell you that you need to put them in, even if you do not itemize. And the error it gives you is very unhelpful, it doesn't say that it's checking the number you entered in for CARES Act donations against what you entered into the itemized list.
