Code J and Pub 590-A have nothing to do with this distribution from a 401(k). Code J is only used with distributions from a Roth IRA.
It seems that the corrective distribution occurred in 2024, so the earnings will be present in boxes 1 and 2a on a code-8 2024 Form 1099-R (or, if the excess a contribution to the designated Roth account in the 401(k), codes B and 8 together).
