@retshop
I do not believe it is possible to fix the return in 2021 without fixing the 2020 return and then transferring the rectified 2020 return into your 2021 return (that should absolutely resolve the issue).
However, it is unclear whether the 2020 return was transmitted with the erroneous information (K-1 marked final) or if that occurred after filing with a subsequent update or other, post-filing, anomaly. Regardless, if it is only the K-1s, then there should not really be a huge issue unless the members/partners entered them as final in the personal tax returns.
