I paid 1500.00 to IRS in August of last year. I do not see this in my 1040 - I do not remember TurboTax asking me to enter this while I was completing the form

To enter, edit or delete estimated taxes paid (Federal, State, Local) -

Click on Federal Taxes (Personal using Home and Business)
Click on Deductions and Credits
Click on I'll choose what I work on (if shown)
Scroll down to Estimates and Other Taxes Paid
On Estimates, click on the start or update button

Federal estimated taxes paid are entered on Form 1040 Line 26

What was the $1,500 for?  Was it your 2023 tax due?  Or did the IRS send you a letter that you owed for a prior year or something?   Or did you make an Estimated payment for 2024?