Retirement tax questions

I believe I could also take the position that I consulted TDAmeritrade, and they told me what I had to do to create the Rollover account, so yes it was a mistake from them.

Can you provide additional detail on the 6% tax (i,e, IRS regulation #)?

I ask because I see some references that it applies to end of year account values, and I see references to "timely correction" without an excise tax would have been Oct 15 of the year after the mistake was made, so October 15, 2022.  Also, if this is what needs to be done, what IRS form is used to document and track this.

If this is the solution, I am trying to understand why I couldn't get that response from the supposed Tax Experts employed by TurboTax.

Thanks for your help so far.