Paid it back, where? To whom?

I found this article for you: https://www.irahelp.com/slottreport/what-happens-if-i-terminate-employment-unpaid-401k-loan

You have to know what else transpired: she/he violated the loan arrangement, terminated plan, terminated employee, this employer does not offer repayment window (but that article tells you how to do it for IRS acceptance as a rollover), etc.