Are there any mandatory state taxes in W-2 box 14? That would be included. If you had a refund on your 2023 state tax return there's also a complicated calculation on the State and Local Income Tax Refund Worksheet that can result in part of that refund being included in Schedule A line 5a.
Schedule A line 5a comes from line 1h on the Tax and Interest Deduction Worksheet. Open the Tax and Interest Deduction Worksheet in forms mode. Right click the amount on line 1h and select Data Source from the pop-up menu. It will give you a list of everything that's included, with links to where the amounts come from.
