Why is the depreciation diff for "New rental proterty" vs "Rental Property"?

I rented my property out in Sep 2020. When I add the rental property in TurboTax with "First year rented" and "Converted home to rental" checked, I got only $4,009 depreciation deduction for 2020 in the end, saying "This was calculated off your total depreciable amount of $1,134,136." But with $1,134,136 basis starting in September, should it not depreciate $1,134,136*0.01061 = $12,033 in the first year? TurboTax actually does give a depreciation of $12,029 if I add the property without checking "First year rented" and "Converted home to rental", same depreciable amount. What has caused the difference?