The Effect of Tax Code Changes on Refunds Posted on 2/8/2019 at 17:20:06 by Bill Crawford, (14)
The below-linked article indicates that quite a number of folks got a smaller tax refund for 2018 than for 2017.
It sounds like this was due to smaller withholdings and to changes in the itemized tax deductions.
I have to say that I was one of the ones who received quite a bit larger refund for 2018; this, due to the doubling of the standard deduction.