Mystery solved!
First mystery. $1000 from 2022 tax refund was applied to 2023 estimated tax. I sent in another $2000 in 2023. I entered $1000 and $2000 as total estimated tax payments for 2023. TT added another $1000 as it remembered that it had applied $1000 from 2022 tax refund. So TT entered $4000 on line 72.
Second mystery. So total estimated tax payment should be only $3000, but State Board said $3500. My fault. I forgot I made another payment of $500!
Anyway, it will be nice if TT reminds me tax refund applied from previous year is automatically included, and I do not have to enter it again.
Thanks!