Successor Beneficiary - Missed RMD and Amended Return

Hi - I am a successor beneficiary of an inherited IRA. 

The original owner passed in 2014. The beneficiary passed in 2019. 

I took the RMD in 2019. I did not take it in 2020 due to suspended requirements for the pandemic.

In 2021, my financial advisor advised the wrong amount and did not withdraw enough.

In 2022, my financial advisor sent a letter that they were taking the distribution but did not.  I had spoken to them about setting it up to automatically distribute, which I also thought they did. They subsequently sent a letter stating they were terminating being my advisor due to their own business realignment. 

In 2023, there was no distribution taken. 

In 2024, I realized that I was remiss in RMDs and contacted the firm with the IRA. I received 3 separate distribution transactions for the delta of 2021, for 2022 and 2023. I had them take out an estimated tax withholding. 

My question: Do I submit the 5329 form for all three years with my 2023 taxes (I have an extension), and therefore use my 2023 tax rate... or do I need to submit amended returns and a 5329 form separately for 2021 AND again for 2022? 

I understand that I will have to explain why the RMD was missed and pray that I do not have to pay a penalty.