Why is the federal income that was withheld from me not the same amount that i'm getting as a federal return?

There's no particular reason why you should get all your withheld taxes refunded,   Why do you think you should get it all back?

People who make over certain amount of income will end up with the Govt keeping some or all of their withholding...some folks even have to pay more at tax time!!

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If line 15 on your form 1040 has a positive number in it, then you usually have a tax liability (line 16), and the IRS will keep some or all of your prior withholding.

Now...if you have dependents....the generous Covid rules for the various child tax credits have changed back to ~ those from before covid hit.....So your child tax credits may now be reduced.