Need advice for payroll taxes.

Employers W-2 shows inflated FICA taxes > 6.2 and 1.45 percent. I calculated all paystubs for 2025 and the correct amount was withheld. The YTD deductions on last paystub shows correct withholding. Asked employer for W-2c. W-2c now shows correct FICA tax withholding but now the Fed income tax is inflated and the employer is now saying they will reduce upcoming paycheck to cover the gap in fed income tax because they "paid too much". Obviously something fishy is going on. I told them I will need documentation showing how I was over paid and if they paid fed income tax on our behalf and is now trying to recoup. What do y'all think?