each schedule e page 1 worksheet - ie rental income has a QBI section. in forms mode, you have to scroll down to that section. since QBI began in 2018 you would enter the loss as a negative. it's in the "passive limits" section of the form.
similarly for k-1's from partnerships, S-Corps, and Trusts, the k-1, reported on page 2 of schedule E input worksheet also has a section for each QBI loss carryforward from 2018 but the entry is the Qualified Business Income Carryovers section. similarly, loss c/o are entered as negatives.
