Thanks for that!
IRS is basically saying, "The self-employment tax deduction you received is attributable to your business and therefore reduces your QBI for this 199A deduction"
From page 44, "Thus, for purposes of section 199A,
deductions such as the deductible portion of the tax on self-employment income under
section 164(f), the self-employed health insurance deduction under section 162(l), and
the deduction for contributions to qualified retirement plans under section 404 are
considered attributable to a trade or business to the extent that the individual’s gross
income from the trade or business is taken into account in calculating the allowable
deduction, on a proportionate basis. "
