It's quirky.  If your VA AGI is below the filing threshold, it doesn't matter what the taxable income is, the tax will be $0.  For S/MFS the VA AGI amount is $11,950.  For MFJ it's $23,900.  My guess is that the AGI was lower in 2018 (assuming MFJ here) so no tax.  But 2019 income is higher than $23,900 so, tax.

See the bottom of printed Page 3 (PDF pages 9 or 11 depending on the year):

https://www.tax.virginia.gov/sites/default/files/vatax-pdf/2018-form-760-instructions.pdf

https://www.tax.virginia.gov/sites/default/files/vatax-pdf/2019-760-instructions.pdf

"Complete Form 760, Lines 1 through 9, to determine your
Virginia adjusted gross income (VAGI). If the amount on Line
9 is less than the amount shown below for your filing status,
your Virginia income tax is $0.00 and you are entitled to a
refund of any withholding or estimated tax paid."

Rick (in VA)