Ask CO.
MY STATE REFUND WAS LESS THAN I EXPECTED
The state will send you a letter explaining the change. TurboTax does not get any feedback from your state after your return is accepted, so no one at TT knows why your state refund was less. Did you owe back taxes, child support, or student loans? Traffic fines, etc.?
This information is not provided to TurboTax. You would have to call the CO Dept. of Revenue to see why they made a change. This can happen for reason such as to them having information that does not match what you entered so they make a correction. This can occur due to an entry error or missing W-2 or 1099 that they received that you did not enter on your return. It can also occur because of a refund offset, or an adjustment to a credit or deduction you claimed.