Why is My W-2 has box 2- Federal Income Tax withheld empty?Why, if federal taxes we're deducted from every paystub? Could it be an error?

Why is My W-2 has box 2- Federal Income Tax withheld empty?I find it strange since federal taxes we're deducted from every paystub? Could it be an error in the W-2?
This is the first time ever this happens.