The state standard deduction went up a lot this year, so that reduced your taxable income, but since the increase in the deduction didn’t go into effect until December (it was tied to actual state revenue vs. projections), your boss spent the entire year withholding at the old rate, assuming a smaller deduction amount.

There is no raise to the deduction planned this year regardless of state revenues, so withholdings should match your tax liability this year.

TL;DR, through no fault of anyone but the General Assembly, you paid too much in taxes over the year and got a big refund. Do not expect the same next year.