I was accurate about loss carryovers.
IRS comments (in part) re.199A Regs:
p40 A. Qualfied Business Income
2. Previously Disallowed Losses
The proposed regulations provide that previously disallowed losses or deductions ("various sections cited") allowed in the taxable year are taken into account for purposes of computing QBI so long as the losses were incurred in a taxable year beginning after January 1, 2018. Because previously disallowed losses incurred for taxable years beginning before January 1, 2018, cannot be taken into account for purposes of computing QBI, several commenters recommended that final regulations provide an ordering rule for the use of such losses.
p41 The Treasury Department and the IRS agree that taxpayers with previously disallowed losses for taxable years beginning both before and after January 1, 2018, require an ordering rule to determine which portion of a previously disallowed loss can be taken into account for purposes of section 199A. Consistent with regulations under former section 199, these regulations provide that any losses disallowed, suspended, or limited under the provisions of sections ("var sections cited"), or any other similar provisions, shall be used, for purposes of section 199A and these regulations, in order from the oldest to the most recent on a FIFO basis.