The 2019 tax return has the correct 8606 form with correct contribution basis. IRS didn't seem to have issue with the 2019 tax return. Now the problem is that I filed delinquesnt 8606 forms for each of the years before 2019 to show how I contributed each year and how cost basis gradually increased. I still don't know why I should file 1040x as there should be no change on any numbers on prior 1040 forms.
