I am still slightly confused. So It appears that because the check from Account A was sent in 2021 paid to the "estate of" . The Estate Of- received a 1099R for $343,000. The person Filed the 1041 timely for the year 2021, ignored everything and solely listed the 1099R rec'd for $343,000 and the IRS withdrew the tax (37%). the person who filed the return (Who is also the beneficiary of the estate and not a tax person) never listed a K-1 on the return

So, do I have to file an amended return for the estate(getting back the taxes paid or at this point does both the estate and the beneficiary paid taxes on the $343,000), and then also list a k-1 to the beneficiary for the full $343,000 

I have listed all of the info I know on a previous question