Roth 401(K) Excess Deferral

Due to changing employers, I have excess deferrals to my Roth 401(k) during 2020.

I informed the benefits provider, and received distribution of the excess deferral + earnings on the excess before the required deadline.  The benefits provider makes it clear that the Earnings on the excess deferral are taxable in 2021.  Since this is a Roth contribution, I have already paid taxes on the excess contribution itself during 2020.   The benefits provider is not sending any additional 1099s for 2020.

To address this situation (I interpret as "to inform the IRS that I corrected the excess deferral") TurboTax guides me to:

• add an additional 1099, completing box 1 (I interpret as "Excess deferral + Earnings") and 2a (I interpret as "Earnings").   
• in Box 7, indicate code P.   
• Indicate that the form year is 2021
• When filing 2021 taxes, enter all 1099s that I receive.

My questions:

• Should I use indicator B in box 7?   TurboTax does not comment, but since B indicates Roth, seems appropriate?
• Why is the direction to use code P instead of code 8?   I am finding it confusing which of these codes would indicate that the taxes on earnings are owed in 2021 given that this will be a 2021 form.
• Is there need to use code J in box 7?   This is technically an early withdrawal, but I assume code 7 indicates additional penalty is required, which I don't think is correct--- taxes would be paid by nature of including the earnings in box 2a.

Thank you!