Could the internal Turbo Tax tax tables be wrong? With the same taxable income in both 2018 and 2019 there are hugely different tax amounts due.

My mother-in-law has almost same income every year. She take std. deduction.

$4200 from pension

$3500 from IRA RMD

$15,100 from Social Security

$38,800 Dividends

$6900 Tax exempt Interest

So the total Income is usually approx. $56000 and Taxable is approx. $42,500. No other special situations.

For 2018,  Turbo tax calculated $2,081 tax due. For 2019 it calculated $5,214. Why the big Diff?