No one in this user forum can see your tax return or your screen. There were major tax law changes that began with the 2018 tax year that seem to continue to surprise some people. Personal exemptions of over $4000 per person were removed beginning with 2018 returns.
One thing that may be affecting your refund is that employers began withholding less tax when the new tax law passed. Your paychecks were more, but that means a smaller refund now.
There are a lot of variables that affect your refund or tax due including how much you earned, how much tax you had withheld, your filing status, the number of dependents you claim, your deductions and credits, etc. You may have lost Earned Income Credit or the Child Tax Credit— did a child turn 17? If you received the EIC last year, remember that changes in the amount you earn have a big effect on the amount of EIC you can get. (Sometimes earning more money means less EIC) Are you 65 or older ? If so, your standard deduction is higher. Everyone has a higher standard deduction now so it is harder to use itemized deductions.
And of course, always check your own data entries, looking for errors such as misplaced decimals or extra zeros.
Print out 2018 and 2019 and compare them side by side to see what is different.
One reason is the IRS changed the withholding tables so you got more in your checks during the year instead of a big refund. And there are other tax changes. And any dependents you have are a year older. If you made more income that can reduce some credits you got like the EIC.