Your employer is withholding zero Federal income taxes because employer believes your Taxable Income on your Federal tax return will be zero.
Your dependents create credits which are like a check that pay your taxes.
If you have dependents, you may be filing Head of Household which gives you a Standard deduction of $19,400 in 2022.
So your Box 1 Wages on your W-2 will be reduced by $19,400 and your employer sees another $4,000 of dependent credits which will be used to reduce your tax liability; in other words, employer does not believe you will owe Federal income tax so employer is withholding zero Federal income tax from your paychecks.
