SEPTA has to do with transportation expenses that were handled by your employer. Without looking at your return, we can only guess that you might have had something in one of the boxes of your W-2 dealing with prepaid transportation or the like, which is paid for with pre-tax dollars from your paycheck. SEPTA is state-specific. TurboTax might be detecting that you overpaid and your employer's payroll department should refund you. This makes sense because in 2020 most people did not ride public transportation. However if you got this message last year, it could be that you simply overpaid.
Here is a link to more information about SEPTA. We would suggest you contact your employer to find out more.
