Want to verify how I think this should be played out for 2020 SH's four S Corps:

1 S Corp lost $900k in 2020 (COVID)  (zero basis to deduct any losses at SH level) QBI is negative

1 S Corp profit $45k (20% to QBI based on limitations)

2 S Corps, each with a profit of around $30k (both utilizing Suspended Carryover Losses to offset entire income) 20% to QBI based on limitations.

Looks like all 4 S Corps including the one with huge loss need to be taken into account.

Consequently, due to the one with huge loss, total QBI for 2020 = zero, with huge Carryover to 2021.

Hopefully I am wrong and to treat otherwise wouldn't be wise.