can't answer the law for 2022 per IRC section 1212(c)(1)(A) is a 3 year carryback
tentative loss carryback is $70000 less the $15000 in gain less the actual capital loss deduction allowed for 2022 which normally would be $3000
the loss that can be used in the c/b year is the smaller of a) the net gain from1256 contracts for that year or b) the net capital gain shown on line 16 of schedule D for that year
any amount not used is carried to the second prior year following the same rules then the prior year again following the same rules. if you have no net 1256 gains for 2019 or 2020 then because there is also a loss in 2021 you don't have a carryback.
