How to get invoice withheld and applied prepayment amount in SQL?

Use the following API column in your SQL respectively:
AP_INVOICES_PKG.GET_PREPAY_AMOUNT_APPLIED(AI.INVOICE_ID) PREPAY_AMOUNT_APPLIED
and
AP_INVOICES_PKG.GET_AMOUNT_WITHHELD( AI.INVOICE_ID) AMOUNT_WITHHELD