why didn't the 2020 1099-B reflect those gains? Turbotax would only reflect either what you entered or imported. if the 1099-B was in error, you should have requested a corrected one and reflect that in your 2020 return.
if those gains should have been reflected in 2020 you would need to amend 2020 and pay any taxes owed and then you would get a bill for penalties and interest. if you would still get a refund but smaller, that amount would be forfeited.
if there were no wash sale loss left at the end of 2020, which is what you seem to be saying, 2021 would need to reflect the proper capital gains/losses. you can't properly report realization of those wash sale losses in 2021 if they should have been in 2020.