The qualified business income deduction (QBI) comes from business income that may be reported on line 3 of schedule 1, but may also include income reported on schedule E from an interest you may have in other businesses (line 5 of schedule 1) or from farm income reported on line 6. It may also be affected by certain types of dividend income. It would not necessarily come from line 10 of Schedule 1 as that may include non-business income amounts.
The best way to see where it is coming from is to look on Form 8995 QBI Deduction Simplified Computation. The QBI deduction may factor in reductions from retirement plan contributions as well as capital gain income and other things, so you may not be able to simply take your net business income times 20% to arrive at the QBI deduction amount.
First thing I did was go to Form 8995 on TurboTax Home & Biz to try and see if it would tell me where this number was coming from, but column 1 C just has the NQBI number there with no reference as to where it came from or what where the components that made that number. In previous year's versions, I had not tried this one yet, which ever number was on a particular form you could trace to where it came from and you could follow the logic. Not here, therefore, my question. It's not a biggie, I trust the number is correct but it's just that I would like to know how the NQBI amount was arrived at, since it does not look like any number that I add or subtract from line 10 of Schedule 1.