No one else can see your tax return. The usual reason for owing state tax is that you did not have enough tax withheld from your paychecks to cover your state tax liability. Or did you receive unemployment without having tax withheld---some states tax unemployment. Compare your printed 2019 and 2020 state returns line by line to see what is different. And of course check all of the amounts of income and tax withheld that you entered from W-2's etc to make sure you entered it all correctly. Pay special attention to anything you entered from boxes 16 and 17 of your W-2's.
Which state? Some states changed their tax laws in 2020. Also be sure to check your data entry for any typos.