The QBI loss is only for purposes of the QBI deduction. there is no effect of the QBi on the profit or loss.
Your current year loss would reduce current taxable income
the QBI deduction is a completely separate calculation
example you have a $5K current year business loss and $15K of QBI loss carryover from prior years
your wife has $13K of business income. your current year loss of $5K would be allowed to offset her $13K of income for taxable income purposes. look at schedule 1 line 3
however, for QBI purposes the full $20K of QBI carryover would be used to offset her $13K of QBI income leaving a QBI loss carryover to 2024 of $7K.
further example: should you lose $6K in 2024 while she has $15K of income. for income tax purposes, this will add a net of $9k to taxable income but for QBI purposes the $15K will be offset by your $6K of current year losses plus the $7K carryover leaving $2K of QBI.
