This is for your husband's parents? If yes, then, did you fill out a I-864 or I-864A. As his spouse, and you are combing your income with his, then you would just fill out the I-864A as a supporting household member. A joint sponsor is someone who fills out the I-864 to support the immigrating person fully based on their income.
If he now qualifies with just his income, then I would suggest he completes a new I-864. It will be needed for the interview because the one from 2020 would not have updated information - mainly, 2020 taxes.
What is your in-laws country? Have you checked with the regional forums for you embassy? Do you know if you in-laws might get scheduled for an interview anytime soon? If so, then it would might be better to leave the status alone at NVC and give the new I-864 to your husband's parents to take to the interview. If it seems it will still be a while for the interview, then perhaps wait for next year to have 2021 taxes ready.
Fsdela reacted to SteveInBostonI130 in Changes in income and employment after filing affidavit of support
Fsdela got a reaction from princesstammy in Documentarily Qualified