" I would expect 2% reduce in taxes (~$3,800)"
Your expectation is incorrect. The marginal tax rate of the $2,600 is ($33,017-$32,409) / $2,600 = 23.4%. Only $1,821 of the $2,600 was being taxed at 24% and the other $779 was already being taxed at 22% (as is all of the other taxable income between $89,451 and $190,750).
