ESPP Gain reported on W2, however employer used an after tax Deduction for ESPP Taxes. How do I report this (I did not sale the stocks)?

No sale of stocks, however employer reported an ESPP gain in the income statement for the W2. An After-tax deduction was reported in payslip, however was not reported on W-2. How do I claim this after-tax deduction either for this return or on sale of my stocks?